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THE  NORMAL  AND  PATHOLOGICAL 
HISTOLOGY  OF  THE  MOUTH 


VOLUME  II 
PATHOLOGICAL  HISTOLOGY 


By  the  same  Author 

"An  Introduction  to  Dental  Anatomy 

AND  Physiology:  Descriptive 

AND  Applied,"  1913. 

"Dental  Microscopy,"  a  Handbook  of 
Practical  Dental  Histology. 

First  Edition,  January,  1895. 
Second  Edition,  July,  1899. 
Third  Edition,  May,  1914. 


Part  Editor  of  Tomes' 

"A  Manual  of  Dental  Anatomy" 
Seventh  Edition,  19 14. 


The  Normal  and  Pathological 
Histology  of  the  Mouth 

BEING  THE  SECOND  EDITION  OF 

The  Histology  and  Patho-Histology 

OF  THE 

Teeth  and  Associated  Parts 

REVISED  AND  ENLARGED 
BY 

ARTHUR  HOPEWELL-SMITH 

L.  R.  C.  P.,  LoND.,  M.  R.  C.  S.,  Eng.,  L.  D.  S.,  Eng. 

PROFESSOR   OF  DENTAL     HISTOLOGY,    PATHOLOGY    AND    COMPARATIVE  ODONTOLOGY 
UNIVERSITY    OF     PENNSYLVANIA,     PHILADELPHIA;     JOHN     TOMES    PRIZEMAN    OF 
THE   ROYAL   COLLEGE     OF     SURGEONS    OF     ENGLAND;     MEMBRE   HONORAIRE 
DE    LA    SOCIETE     ODONTOLOGIQUE    DE    FRANCE;     FORMEaiLY   LECTURER 
ON   DENTAL   ANATOMY,    SURGEON   AND   DEMONSTRATOR    OF   DENTAL 
HISTOLOGY    AT    THE     ROYAL    DENTAL    HOSPITAL    OF    LONDON; 
MEMBER    OF   THE   FACULTY   OF    MEDICINE    OF   THE    UNIVER- 
SITY    OF     LONDON;     EXTERNAL    EXAMINER     IN   DENTAL 
SURGERY     AT     THE   UNIVERSITIES    OF   BIRMINGHAM, 
LEEDS   AND   LIVERPOOL;    LECTURER  ON  DENTAL 
SURGERY    AND     PATHOLOGY     AT   THE   NA- 
TIONAL DENTAL  HOSPITAL,  LONDON 

VOLUME  II 


PATHOLOGICAL  HISTOLOGY 


WITH  394  ILLUSTRATIONS 

IN  THE  TEXT,  INCLUDING  343  ORIGINAL  PHOTOGRAPHS 

AND  PHOTOMICROGRAPHS  BY  THE  AUTHOR 

PHILADELPHfA 

P.  BLAKISTON'S  SON  &  CO. 

1012  WALNUT  STREET 


Copyright,  1918,  by  P,  Blakiston's  Son  &  Co 


THE     ai  A  3?  r,  E     PHESS     T  O  R  K    TA 


THE  DENTAL  TISSUES 

CHAPTER  I 

Page 

The  Pathological  Conditions  of  the  Enamel 4 

Introduction.  Developinental  Affections.  Hypoplasia — Its  Defini- 
tion, Etiology,  Gross  Anatomy  and  Histology — Enamel  Nodules — 
Pathological  Pigmentation — Nanoid  Enamel — Rachitic  and  Syphili- 
tic Lesions.  Acquired  Affections.  Abrasion — Absorption — Its 
Definition,  Varieties,  Etiology  and  Histology — Attrition — Erosion 
- — Its  Definition  and  Etiology — Views  as  to  the  Latter — Its  Gross 
Anatomy  and  Histology — Fungoid  Excavation. 

CHAPTER  II 

The  Pathological  Conditions  of  the  Dentine 42 

Developmental  Affections.  Dilaceration — Its  Definition,  Etiology, 
Gross  Anatomy  and  Histology — Gemination — Its  Definition, 
Etiology,  Gross  Anatomy  and  Histology — Lacunar  and  Other 
Defects — Definition  and  Etiology — Congenital  Pigmentation — 
Nanoid  Dentine — Vascular  Channels.  Acquired  Affections.  Ab- 
sorption— Its  Varieties,  Definition,  Etiology,  Gross  Anatomy  and 
Histology — Adventitious  Dentines — Varieties — Structure  of  the 
Areolar,  Cellular,  Fibrillar,  Hyaline,  and  Laminar  Types — Patho- 
logical Pigmentation — Senile  Dentine. 

CHAPTER  III 

The  Pathological  Conditions  of  the  Cementum 80 

Developmental  Affections.  Cement  Nodules.  Acquired  Affections. 
Osseous  Ankylosis  of  the  Teeth — Hyperplasia — Its  Definition, 
Etiology,  Gross  Anatomy  and  Histology — Senile  Cementum. 

CHAPTER  IV 

Dental  Caries loi 

Definition — Etiology — Phases  of  the  Process — Caries  of  Nasmyth's 
Membrane — Histology  of  "White  Spots" — Penetration  of  Enamel 

vii 


Vni  CONTENTS 

Page 
by  Micro-organisms — Zones  in  Enamel — Decalcification  of  Dentine 
— Zone  of  Translucency — Theories  as  to  its  Nature — Opaque  Spots 
— Tubular  Infection  and  Formation  of  "Liquefaction  Foci" — 
Production  of  Cavities — Caries  of  Cementum — "Arrested"  Caries 
— The  Micro-organisms  of  Dental  Caries — Epitome  of  the  Histo- 
pathology  of  Caries. 

CHAPTER  V 

The  Diseases  of  the  Dental  Pulp 143 

General  Characteristics — Hyperaemia  of  the  Pulp — Its  Etiology — 
General  Considerations — Special  Histology — Acute  Inflammation — 
Its  Definition,  Etiologj^,  Terminations,  Signs  and  Symptoms — 
General  Histology  of  Inflammation — Special  Histology — Conditions 
Associated  with  Non-penetrating  Caries — Conditions  Associated 
with  Penetrating  Caries — Chronic  Inflammation — Its  Etiology  and 
Histology — Hyperplasia — Histology — Infective  Gangrenej  of  the 
Pulp — -The  Pathogeny  of  Gangrene  of  the  Pulp. 


CHAPTER  VI 

Injuries  of  the  Dental  Pulp 174 

General  Characteristics — Methods  of  Healing  After  Wounds,  viz., 
After  Small  Traumatic  Disturbances;  After  Wounds  Involving  Large 
Areas;  After  Carious  Exposure;  After  Impacted  or  Non-impacted 
Fracture  of  the  Hard  Parts;  After  Injury  Occurring  in  Cases  of  Non- 
exposure  of  the  Pulp. 


CHAPTER  VII 

The  Degenerations  of  the  Dental  Pulp 187 

Histological  Features  of  Fibroid,  Atrophic,  Fatty  and  Calcareous 
Degenerations. 

CHAPTER  VIII 

The  Pathology  of  the  Pulp  in  Relation  to  Clinical  Dental  Surgery      .    .    .      206 
Introductory — Carious  Lesions — Lesions  Due  to  Tactile,  Thermal, 
Chemical  and  Electrical  Stimulations — Referred  Pain  and  Obscure 
Reflex    Acts — Receptivity  of    the    Pulp;    Its    Hypersesthesia    and 
Dysesthesia — Phases  of  Degeneration. 


CHAPTER  IX 

The  Vascular  Lesions  of  the  Dental  Pulp 232 

Introductory— Anatomical       Considerations^General      Effects — 
Histo-pathology — Causes — Clinical  Significance. 


CONTENTS  LX 

Page 
CHAPTER  X 

The  Morbid  Affections  of  the  Alveolo-dental  Periosteum  ........      254 

Inflammation — Its  Etiology,  Gross  Anatomy  and  Histology — 
Abscess — Dental  Cysts — Definition,  Etiology,  Gross  Anatomy  and 
Histology — Tumours  of  the  Periodontal  Membrane — Those  Belong- 
ing to  the  Type  of  the  Lower  Connective  Tissues — Those  Belong- 
ing to  the  Type  of  the  Higher  Connective  Tissues — Carcinoma. 

.    .  CHAPTER  XI 

"  Pyorrhea  Alveolaris" , 271 

Introductory — The  Gingival  Margin — The  Periodontal  Mem- 
brane— The  Apical  Region — The  Cementum — The  Bone  of  the 
Jaw — Conclusions — Normal  Arrangement  of  the  Osseous  and 
Fibrous  Tissues — Early  Changes  Producing  Osseous  Atrophy — 
Absorption  by  Granulation  Tissue — Chronic  Periostitis  and  Senile 
Changes — "Pockets" — Anatomical  and  Clinical  Observations — 
Summary. 

CHAPTER  XII 

Degeneration  of  the  Periodontal  Membrane 306 

Introductory — The  Fibrous  and  Cellular  Tissues — The  Areolar 
Spaces — Changes  in  the  Neighbourhood. 


THE  ORAL  TISSUES 

CHAPTER  XIII 

The  Pathological  Conditions  of  the  Gums,  Palate,  Antrum  and  Jaws.  ...  322 
Inflammation  of  the  Gum — Hypertrophy  of  the  Gum — Fibroma- 
Sarcoma  —  Endothelioma  —  Papilloma  —  Hcemangioma  —  Osteoma 
— Adenoma — Carcinoma — Syphilis — Inflammation  and  Carcinoma 
of  Lining  Membrane  of  the  Antrum  of  Highmore — Tumours  of  the 
Jaws. 

CHAPTER  XIV 

Diseases  of  the  Oral  Mucous  Membrane       354 

Inflammation — Tuberculosis — Malignant  Degeneration. 

CHAPTER  XV 

Odontomes  and  Odontocelcs 371 

Definition — Classifications — Epithelial   Odontomes — Origin,    Gross 


X  CONTENTS 

Page 
Anatomy  and  Histology — Follicular  Odontomes  or  Dentigerous 
Cysts — General  Considerations — Origin  of  the  Cystic  Fluid — His- 
tology— Compound  Follicular  Odontomes — Radicular  Odontomes — 
Composite  Odontomes — Histology — Odontoceles — Introductory — 
Classification  of  Species  of  Cysts  of  the  Jaws — A  Sub-capsular 
Odontocele — An  Extra-capsular  Odontocele. 

CHAPTER  XVI 

Oral  Microbiology 409 

Introduction — Classification  of  Plants — Classilication  of  Bacteria 
and  Protozoa — Microscopical  Examination  of  Oral  Material — 
Pathogenic  Organisms — The  Pyogenic  Cocci — Filterable  Viruses — 
Adventitious  Bacteria  of  the  Mouth — Micro-organisms  of  Dental 
Caries. 


THE  EXTRA-ORAL  DENTAL  TISSUES 

CHAPTER  XVII 

'Dermoid"  Teeth  or  Teeth  Developed  in  Teratomato 459 

Relations  of  Teeth  to  Teratomata — Varieties — Eruption — Develop- 
ment— Shedding — Anatomy  and  Histology — Bony  Attachments — 
Relation  of  "Dermoid"  teeth  to  Hair — "Dermoid"  Teeth  in  the 
Testis — Conclusions. 


PAKT  I 

THE  DENTAL  TISSUES 


INTRODUCTION 

In  considering  the  many  pathological  conditions  of  the  hard  and 
soft  tissues  found  in  the  oral  cavity,  it  is  convenient  to  arrange, 
group,  and  describe  them  according  to  an  anatomical,  pathological, 
or  clinical  point  of  view.  Each  method  of  treatment  is  of  value, 
but  is  dependent  upon  the  character  of  the  work  for  which  it  is 
made.  Thus  the  clinical  viewpoint  is  of  vast  importance  in  manuals 
dealing  with  the  practice  of  Oral  and  Dental  Surgery,  and  it  is 
obvious  that  the  anatomical  should  be  of  interest  in  a  book  dealing 
with  Histology  and  Pathology. 

Hence  it  follows  that,  as  far  as  is  consistent  and  convenient, 
the  arrangement  of  the  Morbid  Affections  of  the  mouth  and  con- 
taining organs  in  this  and  succeeding  Chapters  is  built  upon  the 
morphology  and  minute  anatomy  of  the  tissues. 

Regarding  the  diseases  of  the  hard  dental  tissues  many  of 
which  are  quite  unique,  it  is  necessary  to  point  out  the  fact  that  few 
are  confined  exclusively  to  one  tissue,  but  that  often  the  surrounding, 
or  sublying  structures  share  them  also.  The  whole  of  the  arbitrary 
classifications  hereafter  adopted,  in  order  to  save  confusion,  must 
therefore  be  considered  in  this  light. 

In  the  three  following  and  other  Chapters  the  various  lesions 
are  placed  in  alphabetical  order. 

The  subjects  of  dental  caries  and  ''pyorrhsea  alveolaris"  have 
been  specially  relegated  to  Chapters  by  themselves. 

As  far  as  the  diseases  of  the  soft  Oral  and  Dental  tissues  are 
concerned,  they  differ  essentially  in  no  characteristics  from  morbid 
conditions  of  other  cellular  and  fibrous  structures.  The  phenomena 
of  inflammation  proceed  on  identical  lines  with  those  elsewhere. 
The  structure  of  tumours  of  the  jaws  is  in  agreement  with  that  of 
those  which  affect  other  regions  of  the  body.  In  consequence, 
however,  of  their  environment,  the  usual  histological  and  patho- 
logical appearances  are  modified  to  greater  or  less  degrees,  and  hence 
are  peculiarly  interesting  and  important. 


CHAPTER  I 
THE  PATHOLOGICAL  CONDITIONS  OF  THE  ENAMEL 

Microscopical  Elements  in: — (i)  Hypoplasia;  (ii)  Enamel  nodules;  (iii) 
Pathological  pigmentation;  (iv)  Nanoid  enamel;  (v)  Rachitic  enamel; 
(vi)  Syphilitic  enamel;  (vii)  Abrasion;  (viii)  Absorption;  (ix)  Attri- 
tion; (x)  Erosion;  (xi)  Fungoid  excavation. 

A.- — DEVELOPMENTAL   DISEASES 

(i)  Hypoplasia 

Definition. — Enamel,  the  surface  of  which  is  more  or  less  covered 
with  pits,  or  fissures,  not  due  to  absorption.  The  term  indicates 
fairly  accurately  the  condition  in  which  the  enamel  is  not  only  re- 
duced in  amount  and  thickness,  but  is  developmentally  defective. 
It  is  the  antithesis  of  hyperplasia,  where,  as  in  the  case  of  cementum, 
the  tissue  is  increased  in  bulk.  The  old  term,  "honeycombed  teeth," 
is  falling  into  desuetude,  as  it  should  do,  inasmuch  as  it  is  an  incor- 
rect and  misleading  expression.  Hypoplasia  was  originally  called 
by  Salter^  "Rocky"  enamel.  The  condition  may  be  (i)  general 
or  (ii)  local. 

Etiology. — The  factors  concerned  in  the  production  of  (A)  General 
hypoplasia  of  the  enamel  are  not  absolutely  determined.  Most 
probably  (i)  the  exanthematous  fevers,  when  sufficiently  acute, 
particularly  measles  and  scarlet  fever,  occurring  during  the  first  and 
second  year  after  birth,  are  the  chief.  The  pathological  changes 
have  also  been  ascribed  (ii)  to  the  effect  produced  on  the  ameloblasts 
by  the  exhibition  of  mercurial  salts  for  the  relief  or  cure  of 
convulsions  during  the  dentition  of  the  child,  (iii)  Lamellar  cata- 
ract is  often  accompanied  by  hypoplasic  enamel.  The  condition 
is  more  likely  to  be  occasioned  (iv)  by  malnutrition  from  im- 
proper dietary.  At  all  events,  it  is  certain  that  it  is  due  to  modified 
function  or  altered  metabolism  on  the  part  of  the  ameloblasts  when 
they  are  most  actively  engaged  in  depositing  lime  salts,  probably 
by  the  process  of  secretion.     This  would  account  for  the  granular 

1  Salter's  "Dental  Pathology  and  Surgery,"  p.  74,  1874. 
4 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


appearance  of  the  rods  to  be  presently  noticed.  Exactly  how  the 
indentations  or  crevices  themselves  are  formed  is  not  known:  it 
may  be  that  some  perverted  state  of  Nasmyth's  membrane  may 
cause  them. 

Suppuration  around  the  root  or  roots  of  deciduous  teeth  may  in- 
duce, (B)  Local  manifestations  of  the  disease  in  the  crowns  of  their 
permanent  successors. 

Hypoplasia  of  the  enamel  is  said  to  occur  in  deciduous  teeth/ 
but  care  should  be  taken  to  discriminate  between  hypoplasia  and 
absorption  of  this  tissue. 


Fig.  I. — Vertical  section  of  a  cusp  of  a  molar  with  hypoplasia  of  the  enamel. 
Prepared  by  grinding.  Unstained.  Magnified  45  times.  e.  Enamel;  F. 
Fissure;  p.  Pit  extending  to  the  margin  of  the  dentine;  d.   Dentine. 

Macroscopical  Appearances. — The  most  prominent  features  of 
hypoplasia  of  the  enamel  are  loss  of  substance,  deepening  of  the 
normal  pits  and  fissures  of  its  surface  in  situations  such  as  the  pre- 
molars and  molars  where  they  exist  normally,  pigmentation,  and 
loss  of  lustre.     The  normal  amount  of  the  enamel  is  considerably 

'Otto  Zsigmondy,  "Beitrage  zur  Kenntniss  der  Entstehungsursache  der 
Hypoplastischen  Emaildefecte."  Trans.  World's  Columbian  Denial  Congress, 
p.  48,  1894. 


THE   DENTAL   TISSUES 


Fig.  2. — Sagittal  section  of  an  inciaor.  Prepared  by  grinding.  Unstained. 
Magnified  45  times.  E.  Deeply  pigmented  hypoplasia  enamel;  I. L.  "Interrup- 
tion lines;"  Fi.  Fissure  or  pit  on  labial  surface;  F2.  Pit  on  lingual  surface;  d. 
Dentine.      Cf.  Fig.  12,  Vol.  I. 


PATHOLOGICAL    COXDITIONS    OF    THE    ENAMEL  7 

reduced  in  extent.  In  the  molars,  as  well  as  in  other  teeth,  a  pro- 
nounced line  of  demarcation  often  divides  the  ill  from  the  well- 
developed.  The  shrunken  appearance  of  the  crowns  of  molars  seems 
to  heighten  the  effect  of  the  elevation  of  the  cusps,  several  of  which 
may  be  raised  to  pointed  conical  eminences.  The  enamel,  in  addi- 
tion to  loss  of  its  characteristic  appearance^  may  be  pigmented  a 
brown  or  yellow  colour. 

In  the  incisors  and  canines  the  pits  or  grooves  are  sometimes  very 
numerous  and  small,  running  either  in  a  vertical  or  a  coronal  di- 
rection. Sometimes  they  are  distributed  uniformly  over  the  crown, 
and  give  it  a  spotted  aspect. 

The  extent  of  the  hypoplasia  varies.  The  commonest  condition 
is  that  the  crown  of  the  first  permanent  molars,  incisive  edges  and 
part  of  the  crowns  of  the  incisors,  and  the  cusps  of  the  canines  are 
affected,  the  degree  in  each  case  of  severity  being  similar,  but  of 
extent  unequal. - 

Secondary  Changes. — There  may  be  no  secondary  changes,  the 
enamel  undergoing  no  further  alterations.  But  usually,  marked 
pigmentation  occurs,  and  caries  attacking  the  depressions,  especially 
when  the  dentine  is  exposed  at  the  base  of  the  cavities,  may  lead  to 
fracture  and  loss  of  the  tissue.     "Arrested  caries"  may  also  occur. 

HISTOLOGY 

The  most  striking  appearance,  as  viewed  under  low  power,  is  the 
deeply  pigmented  condition  of  the  enamel.  Dense  bands  of  brown- 
ish colour  extend  throughout  its  substance,  being  particularly 
pronounced  in  the  neighbourhood  of  the  breaches  of  surface  (Fig. 
i).  Brown  and  grey  stripes — "interruption  lines"  alternate, 
with  little  or  no  attempt  at  regularity  (Fig.  2).  The  brown 
striae  of  Retzius,  in  the  majority  of  sections,  are  wanting,  as  also 
are  Schreger's  lines. 

A  diminution  in  the  normal  width  of  the  enamel  is  a  remarkable 

'  As  a  matter  of  fact,  the  enamel  is  often  quite  white,  shiny,  and  smooth  in  the 
areas  between  the  depressions. 

^  In  this  connection  it  is  of  interest  to  recall  the  facts  that  "calcification  cen- 
tres" appear  in  the  tooth  germs  of  the  first  permanent  molars  about  the  eighth 
month  of  intra-uterine  life,  in  the  incisors  about  the  first  year  of  post  natal  life, 
and  in  the  canines  about  the  third  year  of  post  natal  life.  For  detailed  accounts 
of  the  calcification  of  the  teeth  generally,  see  the  author's  "An  Introduction  to 
iK-ntal  Anatomy  and  Physiology:  Descriptive  and  Applied,"  1913. 


.8  THE    DENTAL    TISSUES 

feature.  This  occurs  chiefly  at  the  sites  of  the  excavations  or  sulci, 
though  it  is  certain  that  the  thickness  of  the  tissue  generally  is  not 
so  great  as  usual.     The  surface  is  smooth  and  rounded. 

Under  higher  magnifications  the  most  internal  stained  areas 
are  seen  to  consist  of  masses  of  coarse  granules,  the  rods  individually 
being  ill-formed  and  structureless.  The  brown  patches  at  the 
periphery  of  the  enamel,  however,  show  that  the  striae  resident  in 
the  rods  are  very  pigmented,  being  stained  brown  (Fig.  5),  while 
the  intervals  between  the  striae  shine  with  a  bright  lustre.     But  on 


Fig.    3. — Similar    to     Fig.    i.      Magnified    45    times,     p.   Pigmented    enamel; 
i.S.  Interglobular  spaces  in  the  dentine. 

the  whole  the  rods  are  not  specially  stained.  The  inter-columnar 
cement  substance  is  clear  and  homogeneous.  At  the  free  margin 
the  rods  again  become  opaque  and  devoid  of  any  histological 
elements. 

The  amelo-dentinal  junction  is  sharply  differentiated,  and  con- 
sists, as  in  normal  conditions,  of  a  linear  series  of  myriads  of  con- 
vexities, each  of  which  looks  towards  the  dentine.  The  boundary 
is  often  crossed  by  many  tubes  and  well-organised  enamel  spindles. 


PATHOLOGICAL    CONDIlIONS    OF    THE    ENAMEL  9 

A  little  distance  below  the  dentinal  surface  rows  of  unusually 
large  interglobular  spaces  may  appear  (Fig.  7).  They  correspond 
in  position  to  the  fissures  of  the  surface.  There  may  be  one, 
two,  or  even  three  rows  of  the  spaces.  In  most  cases  they  are  very 
long  and  very  broad.  They  are  the  usual,  but  not  necessarily 
constant  concomitant  of  enamel  hypoplasia. 

The  dentinal  tubules  have  apparently  undergone  no  morpholog- 
cal  alteration.     The  patho-histology  of  Nasmyth's  membrane  over 


Fig.  4. —  The  same  as  the  preceding.  Magnified  750  times.  Shows  the 
faulty,  irregular  character  of  the  enamel  rods,  and  the  pigmentation  of  a  faint 
"interruption  line." 

hypoplasic  enamel  has  never  been  fully  investigated;  but,  according 
to  J.  G.  Turner  {Trans.  Odonto.  Soc.  1916)  it  may  be  considerably 
thicker  than  normal. 


(ii)  Enamel  Nodules 

Definition.— ^moW,    solid,    rounded,    sessile    bodies  with  white, 
shiny,  smooth   surfaces,  situated  below  the  necks  of  maxillary  or 


lO 


THE    DENTAL    TISSUES 


Fig.  5.  —  Hypoplasic  enamel.  Ground  thin.  Unstained.  Magnified  350 
times.  Shows  the  prominence  of  the  striae  of  the  rods  through  pigmentation. 
p.  Patch  of  pigmentation;  s.    Marked  striation  of  rods;  s.e.  Structureless  enamel. 


Fig.  6.  —  Similar  to  the  preceding.  Magnified  250  times,  c.  Granular 
structure  of  the  enamel  rods;  a.  Amelo-dentinal  junction;  i.s.  Interglobular 
spaces. 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL  II 

mandibular  molars  with  the  dentine  and  cementum  of  which  they 
are  intimately  connected.  They  have  been  classified  ^  under  the 
heading  of  composite  odontomes.  They  are  but  rarely  associated 
with  the  mandibular  teeth. 

Etiology. — They  are  produced  by  the  local  development  and  cal- 
cification of  an  aberrant  prolongation  of  a  portion  of  an  enamel 
organ,  which,  while  the  rest  of  the  tooth-band  has  become  atrophied 


Fig.  7. — Similar  to  the  preceding.  Prepared  by  grinding,  and  photographed 
immediately  after  mounting.  Unstained.  Magnified  40  times.  i.L.  "Inter- 
ruption lines;"  i.s.   Interglobular  spaces. 

and  non-existent  persists  in  the  region  of  the  dental  capsule,  and 
after  depositing  lime  salts  disappears. 

Macroscopical  Appearances. — These  little  neoplasms  bear  a  re- 
markable resemblance  in  shape,  colour  and  lustre  to  white  pearls. 
They  present  a  marked  contrast  to  the  dull  surface  on  which  they 
are  located  (Fig.  8). 

Secondary  Changes. — As  far  as  is  known,  they  are  unaffected  by 
disease  or  retrogressive  changes. 

'  "The  Report  on  Odontomes"  by  the  Committee  appointed  by  the  British 
iJental  .Association,  1914. 


12 


THE    DENTAL    TISSUES 


HISTOLOGY 

A  nodule  is  a  hard  mass,  apparently  spherical,  but  in  reality 
hemispherical  or  semi-lunar  in  shape,  consisting  of  a  thick  tubercle 
of  pigmented  enamel,  whose  constituent  parts  are  very  feebly  ma- 
tured. The  rods  are  chiefly  granular  and  homogeneous,  and  their 
transverse  striae  scarcely  visible.  The  striae  of  Retzius  and  lines 
of  Schreger  may  occasionally  be  found.  The  outermost  surface  is 
deeply  coloured  brown,  the  difference  in  the  depth  and  gradations 


Fig.   8. — Four  maxillary  molars  showing  typical  enamel  nodules. 


of  the  stain  being  due,  apparently,  to  the  coarseness  or  fineness  of 
the  granules. 

The  free  edge  of  the  nodule  is  smooth  and  mammillated,  while 
the  attached  margin  is  crescentic  in  outline  and  firmly  adherent  to  a 
button  of  fine-tubed  dentine,  which,  in  itself,  may  exhibit  structural 
defects,  in  the  form  of  interglobular  spaces.  Enamel  spindles  and 
interglobular  spaces,  when  they  do  occur,  are  filled  with  amorphous 
granular  material.  The  crescents  of  the  amelo- 
dentinal  junction  are  not  sharp,  and  many  tubes 
cross  the  boundary. 

Very    rarely,    enamel   nodules,    with    the   patho- 
logical appearances  just  noted,  are  found  imbedded 
in  the  periphery  of  the  dentine  of  teeth  (see  Fig. 
Fig  g — Max-   1 2).     In  these  instances  they  preserve  their  cres- 
illary    molar  ^entic  outlines,  the  difference  being  that  the  dentine 

showing     two  .  r  r  •         1        r  £ 

enamel  nodules,  does  not  project  from  the  surfaces  m  the  form  of 
a  tubercle  or  cone  as  is  usually  the  case;  though  a 
cusp  of  dentine  with  radiating  tubules  does  occupy  the  concavity 
of  the  nodule. 

Nasmyth's  membrane  probably  does  not  exist  as  such  on  the 
exposed  surface  of  the  nodule. 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL  1 3 


HC 


Fig.  10. — Vertical  section  of  an  enamel  nodule.  Prepared  by  grinding.  Un- 
stained. Magnified  20  times,  e.n.  Enamel  nodule;  d.  Dentine;  A.'Amelo- 
dentinal  junction;  H.c.   Hyperplasia  cementum. 


Fig.  II. — A  portion  of  the  preceding  section.  Magnified  250  times,  c. 
Granular  characters  of  the  enamel  rods;  p.  Dense  pigmentation  of  the  enamel 
rods,  totally  obscuring  their  structure. 


14 


THE   DENTAL   TISSUES 


(iii)  Pathological  Pigmentation 

This,  which  is  a  natural  condition  in  the  enamel  of  some  of  the 
families  of  Rodentia,  e.g.,  Beaver,  Coypu,  or  certain  Cetacea,  as  in 
the  persistently-growing  incisor  (tusk)  of  the  Narwal,  is  seldom 
observed  in  human  enamel.  It  must  be  distinguished  from  the 
green  deposits  constantly  observed  on  the  labial  or  buccal  surfaces 


FD 


DE 


Fig.  12. — An  enamel  nodule  surrounded  by  hard  tissues.  Magnified  lo  times. 
E.N.  Enamel  nodule;  d.  Dentine;  f.d.  Structureless  dentine;  c.  Cementum; 
D.E.   Detritus  produced  by  grinding.      {Section  prepared  hy  Douglas  Gahell.) 

of  the  teeth  of  young  children,  due  to  the  agencies  of  chromogenic 
bacteria,  which  probably  primarily  affect  Nasmyth's  membrane.  ^| 

Definition.— h  brownish  discoloration  of  the  enamel  of  teeth. 

Etiology  is  unknown.  The  tissue  changes  most  probably  have 
their  origin  as  a  congenital  defect. 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


15 


Macroscopical  Appearances. — The  enamel  is  bright  and  polished, 
but  is  stained  a  deep  brown  or  yellow  colour. 
Secondary  Changes. — None. 

HISTOLOGY 

There  is  little  to  be  said  about  the  microscopical  structure  of 
this  condition.  High  powers  reveal  the  fact  that  there  are  no 
imbrication  lines;  but  the  terminations  of  the  enamel  rods  seem  to  be 


HC 


Fig.  13. — Vertical  section  of  molar  having  nanoid  enamel.  Prepared  by 
grinding.  Unstained.  Magnified  15  times.  E.  Enamel;  c.  Clefts;  d.  Dentine; 
H.c.  Hyperplasia  cementum. 

covered  with  an  opaque  structureless  narrow  band  of  hard  material, 
which  is  slightly  laminated  in  a  direction  at  right  angles  to  the  rods. 
Groups  of  rods  running  in  a  centrifugal  direction  possess  yellowish 
stride,  with  yellowish  cementing  substance  between.  In  thin  sec- 
tions the  colour  is  scarcely  visible,  but  thicker  masses  of  the  enamel 
reveal  the  staining  very  well. 


i6 


THE    DENTAL    TISSUES 


In  the  sections  examined  by  the  author  there  were  no  striae  of 
Retzius  or  Schreger's  Hnes  or  enamel  spindles;  and  the  tissue  itself 
was  not  particularly  structurally  defective. 

(iv)   Nanoid  or  Dwarfed  Enamel 

Specimens  of  human  teeth  apparently  exhibiting  absence  of 
enamel  or  partial  suppression  of  this  tissue  are  occasionally  met 
with.  In  no  case  however,  investigated  by  the  author,  has  there 
been  entire  absence  of  enamel,  though  in  each  it  is  greatly  attenuated 
and  stunted  in  growth. 


Fig.   14. — Similar  to  the  preceding 


Magnified  35  times. 
Dentine. 


E.    Nanoid  enamel; 


Definition. — ^Loss  of  normal  thickness  of  enamel,  producing 
a  dwarfed  condition,  probably  from  failure  of  nutrition  of  the 
enamel  organ,  with  the  consequent  production  of  its  premature  and 
retarded  growth. 

Etiology. — Perverted  or  loss  of  function  of  the  ameloblasts. 

Secondary  Changes. — Caries  and  fracture. 

Macroscopical  Appearances. — The  crowns  of  the  teeth,  which 
may  themselves  be  fully  developed,  present  rough  lustreless  sur- 
faces, stained  somewhat  a  slight  yellow  colour.  The  probability 
that  the  chromogenic  bacteria  of  the  mouth,  or  organic  post-mortem 


PATHOLOGICAL   CONDITIONS    OF   THE   ENAMEL 


17 


changes  in  the  tissues  have  produced  the  staining,  is  very  remote. 
In  one  unique  instance,  three  of  the  four  third  molars  in  the  same 
mouth  shewed  signs  of  loss  of  enamel  immediately  after  eruption, 
and  it  is  equally  certain  that  caries  was  absent.     In  a  tooth  in  the 


Fig.  15. — A  section  through  the  jaw  of  a  young  ricketty  monkey  during  de- 
velopment, the  deciduous  and  permanent  teeth  being  in  situ.  Prepared  by 
Weil's  process.  Magnified  20  times.  E.  Enamel  of  permanent  tooth  exhibiting 
the  structural  defects  described  in  the  text;  d.  Its  dentine;  p.  Its  pulp;  M. 
Dentine  of  deciduous  tooth.      {The  section  was  prepared  by  Sidney  Spokes.) 

possession  of  the  author,  one  tiny  mound  of  enamel  was  observed 
by  the  naked  eye;  while,  on  microscopical  examination,  two  very 
minute  masses  of  enamel  were  discovered  over  one  of  the  cusps  of 
this  anomalous  tooth,  which  in  itself  was  exceedingly  dwarfed  and 
misshapen. 


THE    DENTAL    TISSUES 


HISTOLOGY 


The  strias  of  the  enamel  rods  are  very  conspicuous,  and  the  inter- 
columnar  substance  marked.  A  tinge  of  yellow  pigmentation  is 
discernible  in  places.  Numerous  microscopic  clefts  pass  in  from 
the  free  surface  of  the  tooth  for  varying  distances.  These  are  not 
due  to  manipulative  processes  consequent  on  the  act  of  making  the 
section. 

The  dentine  is,  as  a  rule,  normal  (Fig.  13);  though  in  the  last- 
named  specimen,  interglobular  spaces  and  vascular  canals  were 
found  in  places. 


Fig.   16. — A     portion     of    the    preceding.      Magnified    50    times. 

D.   Dentine. 


Enamel: 


(v)  Rachitic  Enamel 

Little  is  known  of  this  condition:  but  sections  lent  to  the  writer 
by  Mr.  Sidney  Spokes,  and  photographed  (Figs.  15  and  16)  show 
that  during  development,  certain  large,  numerous  clefts  possibly 
containing,  in  the  recent  state,  soft  material,  can  sometimes  be 
observed  on  the  inner  aspect  of  the  tissue.  Measurements  of  the 
length  of  the  longest  of  the  spaces  in  this  particular  specimen  showed 
them  to  be  0.5  mm.     The  photomicrograph,  taken  by  the  author 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


19 


from  the  original  preparation,  are  of  the  parts  in  and  around  the 
evolving  permanent  tooth  of  a  monkey  affected  by  rickets,  and  are 
most  likely  perfectly  similar  to  those  obtaining  in  like  circumstances 
in  man. 


Fig.  17. — A  section  of  a  human  syphilitic  incisor.  Magnified  175  times.  It 
.shows  extremely  imperfect  enamel,  the  spaces  of  which  do  not  contain  living 
material,  e.  Structurally  defective  enamel;  i.s.  Interglobular  spaces  in  den- 
tine.     {The  section  was  prepared  and  photographed  by  Leon  Williams.) 

The  enamel  of  the  corresponding  deciduous  tooth  was  likewise 
affected,  but  in  a  slighter  degree. 


(vi)   Syphilitic  Affections 

Definition."  Certain  misshapen,  deciduous  and  permanent  teeth 
associated  with  congenital  and  inherited  syphilis. 


20 


THE    DENTAL    TISSUES 


Synonyms. — "Pegged  teeth,"  "Hutchinsonian  teeth." 
Etiology. — -They  are  the  result  of  stomatitis,  a  secondary  syphihtic 
lesion  inherited  by  children,  in  which  the  influence  of  the  inflamma- 
tion on  the  cells  of  the  enamel  organ  and  dentine  papilla  is  perma- 
nently recorded  in  the  surface  and  shape  of  the  incisors,  canines  and 
first  molars. 

The  SpirochcBta  pallida,  according  to  Cavallaro  of  the  Univer- 
sity of  Florence,  "Nouvelles  Observations  sur  la  Dentition  chez 
les  Syphilitiques  Hereditaires,"  1909,  can  be  demonstrated  in  the 
dental  capsule,  and  in  the  pulp  on  the  walls  and  in  the  neighbour- 
hood of  the  blood-vessels. 


Pig.  18. — A  portion  of  the  enamel  from  the  preceding  section.  Magnified 
600  times.  It  shows  lacuna-like  spaces  found  in  syphilitic  enamel.  {Photomicro- 
graph by  Leon  Williams.) 

In  the  same  year,  also,  this  organism  was  observed  in  the  den- 
tal tissues  by  Professor  Pasini  of  Milan,  and  Assistant  Professor 
Lombardo  of  Modena. 

Macroscopical  Appearances. — The  maxillary  incisors  are  most 
commonly  affected,  and  present  characteristic  and  unique  appear- 
ances. These  are  (i)  a  slight  notch  or  groove,  crescentic  in  shape, 
on  the  cutting  edge;  and  (ii)  smallness  of  the  teeth  themselves, 
which  have  convex  sides  and  rounded-off  angles. 

The  mandibular  incisors  are  usually  conical  and  small. 

Secondary  Changes. — -None. 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


21 


HISTOLOGY 

The  surface  is  not  absolutely  smooth,  but  "contains  pits  which 
are  filled  with  micro-organisms  of  a  reddish-brown  colour,  thus 
indicating  that  caries  is  not  in  progress.  The  enamel  rods  are 
poorly  calcified;  large  lacuna-like  spaces,  which  appear  to  be  filled 
with  organic  matter,  are  seen,  some  of  which  have  radiating  proc- 


FiG.   19. — Another  portion  from  the  same  section.      Magnified  800  times. 
(Photomicrograph  by  Leon  Williams .) 

esses,  while  others  communicate  with  the  dentine  by  means  of 
canals."  (Leon  Williams.)  Other  portions  exhibit  large  cavities 
of  various  shapes.  The  dentine  contains  interglobular  spaces 
(see  Figs.  17  and  20). 

B. — ACQUIRED   DISEASES 

The  morbid  affections  of  the  enamel  which  have  been  acquired 
since  its  full  maturity  has  been  reached  are  of  interest,  because, 


22 


THE    DENTAL    TISSUES 


as  a  rule,  they  are  inseparable  from  certain  lesions  of  the  neigh- 
bouring dentine  and  cementum.  The  dental  pulp,  entirely  un- 
affected by  the  retrograde  changes  which  have  taken  place  in  the 
development  of  the  teeth,  too,  often  suffers.  Naturally  also,  local 
conditions  play  a  great  part  in  the  immediate  causation  of  this 
group  of  acquired  diseases,  although  erosion  probably  of  all  enamel 
lesions  may  be  predisposed  to  more  by  general  systemic  dyscrasia 
than  by  inflammatory  conditions  or  physical  disturbances  of  the 
mouth. 

(vii)  Abrasion 

Definition. — ^A  term  applied  to  the  rapid  wasting  and  destruction 
of  enamel  and  dentine  by  friction  set  up  by  foreign  bodies. 


Fig.  20. — A  portion  of  the  dentine  from  the  preceding  section.  Magnified 
250  times.  It  shows  the  interglobular  spaces  of  syphilitic  dentine.  {Photomicro- 
graph by  Leon  Williams.) 

Etiology. — Injury  by  mechanical  appliances  around  the  teeth  and 
friction  from  careless  or  excessive  use  of  the  tooth  brush  are  said  to 
be  potent  factors  in  its  causation. 

Macroscopical  Appearances. — The  cavities  on  the  surface  of  the 
crown  are  very  fiat,  dull,  rough  and  superficial,  being  stained  some- 
what yellow.  The  outline  is  usually  ovoid.  Hyperaesthesia  may 
or  may  not  be  present. 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL  23 

Secondary  Changes. — Caries,  fracture,  secondary  dentine  in  the 
pulp  chamber. 

HISTOLOGY 

Early  stages  show  a  breach  of  surface  at  the  cervical  region  of  the 
teeth,  with  loss  of  the  thin  edge  of  enamel  and  cementum.  Pig- 
mentation is  present.  The  dentinal  tubes  appear  similar  to  those 
of  attrition.  There  is  this  marked  difference,  however,  between 
the  two,  viz.,  caries  may  proceed  more  or  less  rapidly  in  the  former, 
and  not  at  all  in  the  latter.  Later  developments  lead  to  softening 
of  the  dentine  matrix,  deeper  invasion  of  micro-organisms,  and 
destruction  of  the  hard  parts  around  the  cavity. 

(viii)  Absorption  of  Enamel 

There  are  two  kinds  of  absorption  of  enamel— (a)  external  and 
(iS)  internal.  Both  rare,  the  former  may  be,  in  its  earliest  stages, 
unassociated  with  absorption  or  any  morbid  change  in  the  dentine, 
— ^though  at  times  it  may  accompany  absorption  of  both  dentine  and 
cementum — and  proceeds  from  without  inwards;  while  the  latter 
is  wholly  an  occasional  accompaniment  or  corollary  of  the  phenomena 
of  dental  caries,  and  proceeds  from  within  outwards. 

Definition. — That  loss  of  enamel  substance  after  the  tissues  have 
been  fully  completed,  which  is  due  to  pathological  and  not  physical 
or  physiological  or  mechanical  causes. 

{a)  External  Absorption 

Etiology. — Probably  sometimes  the  result  of  {a)  acid  solutions 
coming  into  immediate  contact  with  the  surface  of  enamel  when 
there  has  been  some  localised  suppuration:  and  sometimes  {0)  the 
effect  on  the  enamel  surface  of  the  functional  activities  of  osteoclasts. 
The  anomaly,  which  is  rare,  can  be  observed  in  connection  with  the 
retarded  eruption  of  teeth  in  apparently  edentulous  mouths,  where 
inflammation  of  the  soft  parts  in  the  neighbourhood  of  the  tooth 
has  been  induced  by  pressure  from  artificial  dentures.  In  certain 
cases  brought  under  the  immediate  notice  of  the  author  (a)  mal- 
placed  canines  undergoing  moliminous  eruption  in  an  inverted 
position  had  been  the  cause  in  two  instances;  and  in  a  third  {b)  an 
unerupted  third  mandibular  molar  was  the  affected  tooth. 

Macroscopical  Appearances. — As  one  type,  the  following  descrip- 
tion may  be  given  of  one  of  these  specimens.^     The  crown,  retaining 

'  See  "A  Case  of  Retarded  Eruption,"  by  Warburton  Brown.  Journal  Bril. 
Denial  Associalicn,  June.  iqoo. 


24  THE    DENTAL    TISSUES 

in  some  measure  its  original  conical  form,  was  deeply  hollowed  out 
by  means  of  curious  excavations,  some  of  which  penetrated  the 
pulp  cavity  (see  Fig.  21).  The  surface  was  pitted  and  brown 
in  colour.  Its  cervical  measurement  was  22  mm.,  and  a  large  cavity 
13  mm.  in  length,  extended  round  the  labial  and  distal  surfaces  when 
the  tooth  was  viewed  in  its  normal  position.  The  enamel  and 
dentine,  as  a  thin  shell,  were  complete  over  half  the  labial  and  half 
the  mesial  surface. 

The  crown  was  greatly  pitted,  having  a  deep  fissure  in  the  distal 
surface,  as  is  seen  in  the  photograph  (Fig.  22).  It  was  attached 
to  the  neck  of  the  tooth,  mainly  on  its  lingual  aspect — (Fig.  23) — 
as  well  as  by  means  of  a  column  of  dentine  in  the  central  axis  of  the 


A--^f   B  C-- 


Fig.  21.  Fig.  22.  Fig.  23. 

Fig.  21. — The  labial  aspect  of  the  unerupted  tooth  described  in  the  text: 
Fig.  22. — Its  distal  surface;  Fig.  23. — Its  lingual  side.  Note. — The  surfaces 
of  this  tooth  are  named,  as  if  the  canine  had  finally  erupted  in  a  normal  manner, 
and  assumed  a  normal  position  in  the  dental  arch.  A.  Deep'  excavation;  b. 
Absorption  extending  to  the  pulp  cavity,  the  side  of  which  is  seen  at  c. 


tooth,  which  occupied  what  was  probably  the  original  pulp  chamber. 

The  total  area  of  enamel  present  was  about  2  mm.  square. 

The  tooth  generally  was  normal  in  size,  yellowish  in  colour 
(indicating  age),  and  had  some  slight  amount  of  hyperplasia  of  the 
cementum  over  its  apical  region. 

Secondary  Changes. — None  usually;  but,  exceedingly  rarely ,^ 
deposition  of  bone. 

HISTOLOGY 

In  {a)  cases  the  minute  anatomy  is  interesting,  as  Howship's 
foveolae,  almost  universally  associated  with  absorption  of  the  hard 
tissues  of  teeth  or  bone,  are  entirely  wanting.  The  outlines  of  the' 
cavity  are  irregularly  flat  or  oval,  possessing  none  of  the  round 
bay-like  recesses  seen  in  absorption  in  other  tissues.  Although 
these  absorption-areas  appear  to  be  wanting,  it  would  be  difficult 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


to  explain  the  presence  of  such  large  excavations  in  the  hard  parts, 
if  the  question  of  osteoclastic  activity  were  put  entirely  out  of  court. 
Hence  it  would  seem  reasonable  to  suppose  that  the  greater  pro- 
portion of  the  spaces  had  been  produced  by  the  functions  of  these 
cells. 


PE 


A  A 


Fig.  24. — External  absorption  of  enameL  Prepared  by  grinding,  and  stained 
by  impregnation  with  coloured  collodion.  Magnified  40  times,  e.  Enamel  of 
normal  structure;  p.e.  Pigmented  enamel;  a. A.  Absorption  areas  filled  with 
osseous  material;  b.  Trabeculae  of  compact  bone;  d.   Dentine. 

The  enamel  rods  appear  as  if  broken  off,  and  at  the  extreme  edge 
there  is  a  slight  dissolution  of  their  intercolumnar  cement  substance. 
There  may  be,  or  there  may  not  be,  some  pigmentation  of  the  parts. 

It  is  extreme  conditions,  and  such  as  that  already  cited  in  full, 
which  are  accompanied  by  absorption  of  dentine. 

In  the  (/3)  case  of  a  specimen,  probably  quite  unique,  for  which 


26  THE    DENTAL    TISSUES 

the  author  acknowledges  his  indebtedness  to  Sir  Francis  Farmer,  re- 
markable absorption  had  occurred,  and  had  been  followed  by  a 
most  unmistakable  deposition  of  cancellous  bone  (see  Fig.  24). 
Here  the  foveolae  of  Howship  are  clearly  distinguished,  loss  of  enamel 
having  in  some  parts  extended  almost  to  the  amelo-dentinal  junc- 
tion. Osseous  material,  easily  recognised  macroscopically  as  well 
as  by  the  microscope,  occupied  the  excavations  and  practically 
restored  the  greater  part  of  the  absorbed  crown  of  the  tooth  to  its 
normal  height.  The  history  of  the  tooth  in  no  wise  suggested 
this  interesting  histological  abnormality. 

(/3)  Internal  Absorption 

Etiology. — Caries  of  dentine. 

Secondary  Changes. — Deposition  of  calcified  material  (osteo- 
dentine)  may  occur,  as  in  the  case  recorded  by  Mr.  J.  A.  Woods, 
"A  case  of  Absorption,"  Journal  British  Dental  Association,  April, 
1902,  pp.  193-197  (see  Figs.  25,  26). 

HISTOLOGY 

In  a  letter  to  the  author  Mr.  Woods  describes  the  condition  as 
follows: — 

'Mr.  F.  Rose,  at  a  meeting  of  the  British  Dental  Association, 
showed  a  partly  absorbed  maxillary  third  molar  which  he  had  re- 
cently removed.  It  came  away  without  using  any  force  and  prac- 
tically left  no  socket,  and  only  a  very  shallow  crown.  On  naked  eye 
examination  it  appeared  to  be  merely  the  crown  of  a  tooth,  and  to 
consist  mainly  of  the  enamel  filled  with  a  somewhat  soft  calcareous 
mass.  He  offered  it  for  histological  examination,  and  the  report 
made  at  the  next  meeting  was  as  follows: — 

"'On  scratching  the  inner  part  a  distinct  grating  noise  could  be 
heard,  which  pointed  to  calcareous  elements. 

'"On  proceeding  to  cut  a  section,  I  found  it  would  be  necessary 
to  make  an  ordinary  ground  one,  as  a  decalcified  section  would  not 
show  any  of  the  soft  tissues,  which  had  already  been  destroyed 
by  drying,  etc.  It  was  not  possible  to  get  a  very  thin  section  without 
running  a  great  risk  of  destroying  the  part  showing  the  new  tissue, 
which,  of  course,  was  the  most  important  portion. 

"'The  accompanying  photomicrographs  are  taken  from  various 
parts  of  the  one  section  and  show  most  of  the  important  points. 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


Pjq_  25. — Internal  absorption  of  enamel,  a.  Enamel;  b.  Normal  dentine 
very  full  of  interglobular  spaces;  c.  Cavity  in  the  dentine  formed  by  absorption 
and  then  deposition  of  "  osteo-dentine; "  D.  Enamel  penetrated  and  absorbed 
and  filled  in  with  "osteo-dentine."      {Photomicrograph  by  J.  A.   Woods.) 


Fig.  26. — A  higher  magnification  of  the  preceding,  showing  absorption  of  the 
dentine  and  enamel  from  the  pulp  surface,  and  deposition  of  "osteo-dentine." 
A.  Enamel;  B.  Normal  dentine;  c.  Deposition  of  "  osteo-dentine"  (?)  in  enamel. 
(Pholomicrograph  by  J.  A.  Woods.) 


28 


THE    DENTAL    TISSUES 


"  'A  low  magnification  showed  that  a  large  portion  of  the  normal 
dentine  had  undergone  absorption,  and  that  in  one  part  (a  cusp  of 
the  molar)  the  inner  surface  of  the  enamel  had  been  removed.  All 
this  normal  tissue  has  been  replaced  by  a  mass  of  cancellous  calca- 
reous tissue  which  can  probably  be  best  termed  osteo-dentine. 


Fig.  27. — Vertical  section  of  molar  showing  internal  and  external  absorption 
of  enamel  and  dentine.  Prepared  by  the  Koch-Weil  process.  Stained  with 
Grenacher's  alcoholic  borax-carmine.  Magnified  45  times,  d.  Primary  dentine; 
B.  Compact  but  irregularly  formed  bone  filling  up  pulp  cavity;  a.  Compact 
bone  filling  up  absorption  area  in  primary  dentine;  c.b.  Bridge  of  compact  bone 
crossing  over  areas  of  internal  and  external  absorption. 

"'Fig.  25  is  a  rather  higher  magnification  of  the  same  part. 
It  will  be  observed  that  the  dentine  contains  a  large  number  of 
interglobular  spaces;  this,  however,  is  not  by  any  means  uncommon 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL  29 

in  third  molars.  It  will  also  be  observed  that  in  several  places  the 
absorption  has  penetrated  the  dentine  in  different  places,  and  so  one 
section  gives  the  appearance  of  several  isolated  patches  of  absorption. 

'•  'The  deposited  material  consists  of  spicules  as  seen  in  cancellous 
bone,  the  spaces  being  probably  filled  in  the  recent  condition  with 
pulp  matter.  The  presence  of  lacunae  can  be  seen  in  various  parts 
of  the  osteo-dentine. 

"  'Fig.  26  gives  a  clearer  view  of  the  absorption  of  the  dentinal 
surface  of  the  enamel  with  the  new  material  in  situ. 

'"Another  portion  of  the  section  shows  a  patch  of  cementum, 
part  of  which  has  been  removed  by  absorption  and  osteo-dentine 
has  taken  its  place.'  " 

(ix)  Attrition 

Definition.— GrSLdual  wearing  away  of  the  hard  parts  through  the 
physical  and  physiological  agencies  of  mastication  of  food. 

Etiology. — A  constant  accompaniment  of  senility,  it  is  probable 
that  in  the  young  it  may  occur  under  the  influence  of  certain 
mechanical  forces,  the  result  of  imperfect  occlusion.  In  the  former 
it  is  a  general  condition,  in  the  latter  localised. 

Macroscopical  Appearances. — The  morsal  surfaces  of  molars 
present  a  bright  polished  flattened  table-land  of  hard  tissue.  An- 
terior teeth  may  be  worn  away  so  that  half  the  crown  of  the  tooth 
may  have  disappeared  (see  Fig.  28).  Tartar  is  often  present  over 
the  roots  of  these  teeth. 

Secondary  Changes. — Fracture,  formation  of  secondary  dentine 
in  the  pulp. 

HISTOLOGY 

The  enamel  is  very  pigmented,  and  the  rods  are  cleanly  cut 
at  right  or  acute  angles  to  their  courses.  The  primary  dentine  is 
free  from  caries,  but  sUghtly  coloured  in  patches  which  run  through- 
out its  entire  thickness.  The  dentine  is  cut  transversely  or  tan- 
gentially,  sometimes  at  right  angles  to  the  tubules,  at  others  parallel 
with  them.  The  cut  is  sharp,  and  looks  as  if  made  by  a  keen  razor. 
Interglobular  spaces  are  frequently  present  in  greater  numbers 
than  usual. 

The  secondary  dentine  is  well  formed  and  fine  tubed,  and  fills 
most  thoroughly  the  coronal  and  cervical  regions  of  the  former  pulp 
cavity. 


30 


THE    DENTAL    TISSUES 


(x)  Erosion 

Definition. — Progressive  destruction  of  the  exposed  surfaces  of 
teeth,  producing  cavities  which  are  peculiarly  dense  and  polished, 
and  in  the  majority  of  instances  hypersensitive  on  receiving  tactile 
impressions. 

Synonym. — "Cuneiform  defects." 


Fig.  28. — Sagittal  section  of  a  human  incisor,  showing-  marked  attrition  of 
the  crown.  Prepared  by  grinding.  Unstained.  Magnified  12  times.  A.  Worn 
surface  of  the  tooth;  d.    Dentine;  s.D.   Secondary  dentine;  p.  Pulp  cavity. 


Etiology. — ^Tattle  is  known  as  to  the  origin  of  this  common  con- 
dition which  is  found  in  the  teeth  of  man  the  wide  world  over.  Much 
has  been  written  on  the  subject,  and  many  experiments  to  induce 
it  artificially  have  been  performed. 

In  England  the  lesion  is  usually  ascribed  to  gout  or  allied  diseases, 
affecting  the  small  mucous  glands  of  the  lips  or  gums,  by  setting 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL  3 1 

up  a  State  of  local  congestion,  and  causing  these  bodies  to  pour  out 
an  acid  instead  of  an  alkaline  or  neutral  secretion.  This  acid  mix- 
ture attacks  the  enamel  or  dentine  or  cementum  of  teeth  at  their 
cervical  margins,  and  decalcifies  those  tissues. 

It  is  exceedingly  probable,  however,  that  the  condition  is  pre- 
disposed to  by  the  denudation  of  dentine  at  the  necks  of  teeth  by  the 
thin  edges  of  enamel  and  cementum  which,  as  a  rule,  overlap  it, 
when — in  other  words — these  two  tissues  do  not  meet  bout  a  bout 
(see  Chap.  Ill,  Vol.  I). 

The  action  on  or  morbid  changes  in  Nasmyth's  membrane  are 
entirely  unknown.  Tomes^  attributes  the  aiJection  to  a  chemical 
solution  of  the  tooth  from  acids  generated  by  the  fermentation  of 
mucus,  or  this  material  affording  a  suitable  nidus  for  acid  fermenta- 
tion. Salter  combines  abrasion  and  erosion  under  the  inclusive 
title  of  "Surface  wear,"  and  he  divides  the  causes  into — 

(a)     Predisposing — inherent  softness  of  structure,  as  in  syphil- 
itic teeth: 
(P)     Exciting — molar-mastication    by    incisors,    gritty    food, 
hard  tooth-brush,  and  friction  from  wearing  a  denture. 

On  the  Continent  of  Europe,  six  chief  views  are  held: — 

1.  The  C hemic 0 -mechanical  Theory,  supported  by  Bastyr, 
Brandt,  Sheff,  Shlenker,  and  Walkhoff,  in  which  an  exceed- 
ingly thin  layer  of  dentine  is  decalcified  by  the  constant 
influence  of  weak  acids  generated  in  the  mouth,  and  finally 
removed  by  mechanical  means,  such  as  tooth-brush,  powders, 
etc.; 

2.  The  Mechanical  Theory,  due  to  attrition  by  friction  of  food, 
etc.,  advocated  by  Parreidt  and  Niemeyer; 

3.  The  Chemical  Theory  of  Baume; 

4.  Caries  by  Leber  and  Rottenstein,  Magitot,^    etc.; 

5.  The  Exfoliation  Theory  of  Baume,  which  maintains  the  hy- 
pothesis that  the  superficial  layers  of  the  dentine  not  covered 
by  gum  or  enamel  "die,"  and  fall  off  mechanically,  the 
polishing  of  the  denuded  spaces  being  brought  about  by  the 
rubbing  of  the  lips,  etc. ; 

6.  The  Dechondration  or  Decalcification  of  the  Dentine  Theory 
of  Znamensky.''^     According  to  this  careful  observer  enamel 

'Tomes  &  Xowell:  "A  System  of  iJental  Surgery,"  1906. 
^  "Recherches  sur  la  Carie  des  Dents,  Paris,  1871." 

^  "On  the  question  of  the  origin  of  the  Cuneiform  Defects  of  Teeth."  Journal 
I'ril.  Dc.nl.  Assoc,  \)\).  X  c.l  scq.,  i8gS. 


32  THE   DENTAL   TISSUES 

plays  no  part  in  the  process;  but  there  is  mechanical  removal 

of  isolated  particles  of  lime  salts  in  the  eroded  regions.     This 

is   due    to   "unequal   abstraction  of   the   'gelatine-yielding' 

substances  of  the  dentine,"  and  the  subsequent  swelling  of  its 

organic  constituents. 

Erosion  sulci  have  been  said  to  have  been  found  on  human  teeth 

worn  on  a  denture  as  substitute  in  case  of  loss,  and  also  in  ovarian 

teeth  (see  page  467). 

Macroscopical  Appearances. — The  cavity  of  erosion  is  a  sharp- 
edged,  smooth,  highly  polished  groove  at  the  necks  of  teeth,  running 
transversely  to  their  axes.  In  position,  these  acquired  defects  are 
most  often  seen  on  the  labial  or  buccal  aspects,  and  only  very  rarely 
over  the  lingual  or  palatal  sides  of  the  teeth.  In  outline  they  are 
more  or  less  wedge-shaped,  with  edges  sharply  cut 
and  well-defined.  Their  surfaces  are  smooth, 
bright  and  polished;  by  means  of  a  hand  lens, 
saucer-like  cavities  may  sometimes  be  discerned. 
If  these  tiny  subsidiary  excavations  or  spaces  exist 
\'  ^  "  .       in  great  numbers,   they  may  impart  a  dull,  even 

A  B  rough,  surface  to  the  floor  and  walls  of  the  grooves. 

Fig.  29. — Max-    which  then  may  be  stained  any  colour,  from  yellow 

Lnd^mLlllary  left     ^^  ^^°^^'  ^^^^^'  °^  ^^^^  S^^^^"      ^^  ^^®P  g^Oving 

first  premolar,    the  enamel  is  undermined.     In  number,  as  a  rule, 
from  mouth  of  a  j  file-like   cut   is   seen,    but    occasionally 

managed54,  °_  _  '_  •' 

showing     erosion    several  exist  on  the  cervical  region  of  the  teeth, 
cavities  on  the    especially  when  a  large  portion  is  denuded. 

■palatal     surfaces.  t^  J  b     f 

A.  Distal  aspect  of 

canine,    b.  Mesial  HISTOLOGY 

aspectofpre- 

The  earliest  evidence  of  change,  according  to 
Baume,  is  the  presence  of  cup-shaped  depressions  analogous  to 
Howship's  foveolae,  covering  the  eroded  surface,  which  is  now  un- 
even. Fissures  in  the  neighbouring  dentine  are  simultaneously 
produced.  Further  internally  placed,  is  a  band  of  translucent 
dentine. 

Underwood  has  noticed  {Journal  Brit.  Dent.  Association,  Vol. 
xix.,  pp.  470-2)  a  hitherto  un described  phenomenon  connected  with 
enamel  the  subject  of  erosion.  This  is  the  presence  of  exceed-- 
ingly  tiny  interglobular  spaces,  with  accompanying  calcospherites 
(see  photographs,  Figs.  31  and  32).  These  spaces  are  apparently 
scattered  throughout  the  tissue.     The  writer  adds  that  the  condition 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


33 


Fig.  30. — Coronal  section  of  a  human  molar.  Prepared  by  Weil's  process. 
Magnified  15  times.  E.C.  Erosion  cavity  on  buccal  side  of  the  tooth;  d.t. 
Dentinal  tubes  which  are  probably  completely  calcified;  e.  Enamel;  p.  Pulp; 
p.T.  Band  of  pulp  tissue  which  has  undergone  some  degenerative  (?)  changes. 
The  small  black  masses  in  the  pulp  are  probably  clusters  of  borax  crystals, 
deposited  in  this  manner  by  the  salts  in  Grenacher's  alcoholic  borax-carmine 
stain. 


34 


THE    DENTAL    TISSUES 


differs  in  every  respect  from  the  so-called  erosion  found  in  the  teeth 
of  Oiaria,  first  described  and  figured  by  Murie  in  the  Trans.  Odonto. 
Soc.  of  Great  Britain  for  1870. 

The  granularity  of  the  rods  is  exaggerated. 

That  the  underlying  dentine  is  affected  in  earlier  stages  of  the 
disease  is  shown  by  the  fact  that  the  tubules  are  calcified  throughout. 
That  is  to  say,  in  sections  of  teeth  prepared  by  the  Koch- Weil 
process  they  refuse  to  stain,  but  maintain  a  dark  black  colouration 
through  all  their  length  (Fig.  30). 

The  pulp  has  deposited  a  layer  of  adventitious  dentine  opposite 
the  breach  of  surface.     This  is  truly  Salter's  "dentine  of  repair" 


Fig.  31.  Fig.  32. 

Fig.  31. — Erosion  of  enamel.     Prepared  by  grinding.      Unstained.      Magnified 
750  times.     Shows  interglobular  spaces  and  calcospherites.      {Section  from  the 
collection  of  A.  S.  Underwood.)      {Photomicrograph  hy  Andrew  Pringle.) 
Fig.  32. — Similar  to  the  preceding.     From  the  same  source.      {Photomicrograph 

by  Andrew  Pringle.) 

(see  Fig.  34) .  Its  structure  is  of  an  irregular,  indefinite  character. 
A  well-organised  system  of  tubes  is  wanting,  though  spaces  of  an 
unusual  type  may  be  found.  In  the  photomicrograph  (Fig.  35) 
the  pulp  exhibits  a  different  pathological  condition  to  that  in  the 
Figure  on  page  33.  The  specimen  is  interesting,  showing,  as  it 
does  very  clearly,  the  clefts  described  by  Baume,  the  "dentine  of 
repair,"  and  the  pulp  undergoing  retrogressive  or  fibrous  changes.. 


(xi)  Fungoid  Excavation 

Definition. — The  boring  by  fungoid  organisms  of  large  tubes  in 
the  hard  parts  of  teeth. 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


35 


Fig.  33. 


-Appearances  mentioned  in  the  text  in  the  enamel   of  the   sea-lion. 
{Photomicrograph  by  Andrew  Pringle.) 


SD, 


EC 


Fig.  34. — Erosion,  showing  deposit  of  "dentine  of  repair"  on  the  internal  aspect 
of  the  dentine.  Magnified  40  times,  e.c.  Erosion  cavity;  s.d.  Adventitious 
dentine.     (Section  prepared  by  Douglas  Caush.) 


36 


THE    DENTAL    TISSUES 


EC 


Fig.  35. — Sagittal  section  of  human  incisor.  Stained  with  hseniatoxylene. 
Magnified  45  times,  e.g.  Erosion  cavity  on  surface  of  which  can  be  seen 
Baume's  clefts;  p.  Pulp  tissue  undergoing  degenerative  changes;  f.o.  Atrophic 
odontoblasts;  s.D.  Fibrillar  adventitious  dentine.  {Prepared  by  the  Author's 
process.) 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


37 


Etiology. — It  is  supposed  to  be  due  to  the  peptonising  or  acidify- 
ing effects  of  a  Saccharomyces  equally  in  the  substance  of, the  enamel, 
dentine,  and  cementum.     The  condition  is  extremely  rare. 

Secondary  Changes. — None. 

HISTOLOGY 

Enamel,  dentine,  and  cementum  may  suffer  in  different  degrees. 
Two  interesting  cases  have  been  recorded.     Tomes  {Trans.  Odonto. 


Fig.  36. — Ground  section  of  dentine  and  cementum.  Unstained.  Magnified 
20  times.  D.  Dentine;  b.  Excavations  made  by  the  fungus;  c.  Cementum. 
(From  a  specimen  in  the  collection  of  Charles  S.  Tomes.)  {Photomicrograph  by 
Douglas  Gahell.) 

Sac.  Vol.  xxiv.,  pp.  90-91)  describes  the  first,  where  a  tooth  picked 
up  in  an  ancient  graveyard  had  presumably  been  buried  for  a  great 
number  of  years. 

The  dentine  of  the  root  was  largely  excavated  in  all  directions 
by  tunnels  or  channels  of  uniform  diameter,  which  most  probably 
were  caused  by  a  yeast,  possibly  one  of   t\\c  Saccharomyces.     "In 


38 


THE    DENTAL    TISSUES 


many  places  the  borings  followed  two  directions,  more  or  less  at 
right  angles  to  one  another — the  one  being  along  the  dentinal  tubes, 
the  other  along  places  corresponding  to  those  incremental  layers, 
along  which  disintegrating  dentine  so  often  breaks  up.  Where 
the  dentinal  tubes  were  traversed,  the  enlarged  portion  passed  ab- 
ruptly into  that  which  was  unchanged,  so  that  the  idea  of  a  mere 


^•. 


Fig.  37. — Similar  to  the  preceding,  and  from  the  same  source.  Stained  with 
carmine.  Magnified  40  times.  B.  Borings  in  cementum.  {Photomicrograph 
by  Douglas  Gabell.) 


chemical  solvent  creeping  down  the  tubes  was  negatived.  And 
although  its  usual  course  was  along  lines  which  might  be  regarded 
as  those  of  least  resistance,  it  was  perfectly  capable  of  drilling  the 
dentine  in  any  direction  whatever,  as  is  seen  in  Fig.  36,  in  which 
the  tunnelings  were  in  all  directions,  quite  irrespective  of  the  tubes 
or  the  lines  of  growth." 

"These  sections  prove  that  a  fungus  can,  unaided  or  aided  only 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL 


39 


by  the  decomposition  of  the  organic  material  present  in  dentine, 
drill  freely  in  any  direction." 

Penetration  of  the  cementum  is  clearly  seen  in  Fig.  37. 

The  second  instances  are  those  recorded  by  Professor  Duckworth, 
of  the  Physical  Anthropology  Laboratory  at  Cambridge  University. 
{Trans.  Odonto.  Soc.  of  Great  Britain,  Feb.,  1901,  p.  89),  in  an  article 
entitled  "Some  dental  rudiments  in  Human  Crania."     In  these 


Fig.  38. — Similar   to   the   preceding.     Stained   with    carmine.      Magnified    160 
times.     {Photomicrograph  by  Douglas  Gabell.) 


tiny  calcareous  fragments,  which  probably  represented  vestigial 
third  premolars  (similar  to  those  of  the  New  World  Apes),  true 
dental  tissues  were  found,  the  enamel  and  cementum  of  which  were 
channelled  through  and  through  with  the  borings  made  by  one  of 
the  Blastomycetes. 

The  fragments  came  under  the  personal  notice  of  the  author, 
who   in   a    microscopical   report    wrote:  "Specimen   No.    2154    (e) 


40 


THE   DENTAL   TISSUES 


Columns  (probably  enamel),  chiefly  seen  in  transverse  section, 
though  sometimes  longitudinally  cut.  Not  very  brightly  outlined, 
nor  possessing  marked  striae,  nevertheless  clear  and  unmistakable. 
Numerous  large  tubes  or  channels  with  bulbous  or  rounded  ex- 
tremities run  here  and  there  throughout  the  tissue."  "Root 
portion  of  tooth.  Dentinal  tubes  are  marked  and  when  filled  with 
detritus  from  grinding  very  black.     Cementum  thick,  few  lacunae 


Fig.  39. — Channelling  of  the  enamel.  Prepared  by  grinding.  Magnified 
SO  times.  E.  Enamel;  c.  Sinuous  tube  passing  from  without  inwards  to  end 
at,  A.  The  amelo-dentinal  junction;  d.  Dentine.  {Photomicrograph  by  Douglas 
Gabell.) 


and  canaliculi,  but  incremental  lines  very  apparent.  Traces  here 
and  there  of  fungoid  burrowing.  Specimen  No.  2154  (w)  Transverse 
section  of  dentine.  Cementum  practically  structureless.  Large 
channels  produced  by  Saccharomyces  mycodernia,  confined,  in  this 
preparation  to  the  cementum;  granular  layer  marked," 


PATHOLOGICAL    CONDITIONS    OF    THE    ENAMEL  4 1 

Abnormal  channelling  of  the  enamel  has  been  known  to  occur.  In 
the  specimen,  from  which  Fig.  39  was  reproduced,  a  long  winding 
canal  can  be  observed  leading  from  the  periphery  of  the  tooth  to 
the  amelo-dentinal  junction  which  it  did  not  pierce.  There  is  no 
history  of  the  case.  It  is  certainly  a  developmental  error;  but  its 
method  of  formation  is  absolutely  unknown. 


CHAPTER  II 
THE  PATHOLOGICAL  CONDITIONS  OF  THE  DENTINE 

Microscopical  Elements  found  in: — (i)  Dilaceration;  (ii)  Gemination; 
(iii)  Developmental  defects;  (iv)  Pigmentation;  (v)  Nanoid  dentine; 
(vi)  Vascular  Canals;  (vii)  Absorption;  (viii)  Adventitious  Dentines; 
(ix)     Pathological  Pigmentation;  (x)  Senile  Dentine. 


A. — DEVELOPMENTAL   DISEASES 

(i)  Dilaceration 

Definition. — A  permanent  malformation  of  the  teeth,  usually  in 
their  cervical  or  radicular  portions,  in  vi^hich  the  hard  parts  are 
deviated  from  the  axial  straight  line  in  such  a  way  as  to  form  an 
angle  with  it. 


<^. 


Pig.  41.  Fig.  42.  Fig.  43. 

Dilaceration  of  maxillary  first  incisor. 

Dilaceration  of  another  maxillary  first  incisor. 
— Dilaceration  of  maxillary  first  premolar. 
— Dilaceration  of  maxillary  second  premolar. 


Etiology. — It  is  generally  believed  that  a  severe  blow  in  the  mouth 
may  at  times  produce  such  an  injury  to  the  developing  tooth  or 
enamel  and  dentine  germs  as  to  cause — if  the  traumatism  is  not  too 
great — that  error  of  development  to  which  the  term  dilaceration 
has  been  and  is  still  applied.  The  incautious  removal  of  the  decidu-. 
ous  predecessor  of  a  permanent  tooth  may  hkewise  occasion  it. 
The  anterior  teeth,  with  the  exception,  perhaps,  of  the  canine,  are 
most  commonly  affected. 

Macroscopical  Appearances. — The  tooth  may  be  curved  at  its 
neck  or  anywhere  along  the  extent  of  its  root.     This  bending  may 

42 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  43 

be  a  mere  continuous  flexion  of  its  outline,  the  apex  of  the  root 
terminating  in  a  normal  manner;  or  there  may  be  a  double  curvature. 
More  rarely  the  crown  appears  to  be  joined  to  the  neck  of  the  tooth 
almost  at  a  right  angle  or  acute  angle.  Again,  the  crown  may  be 
apparently  impacted  in  the  body  or  root  of  the  tooth.  Superficially 
examined,  there  are  no  indications  of  morbid  changes,  except  perhaps 
the  occasional  appearance  of  a  mal-formed  crown  and  a  hyperplasia 
condition  of  the  cementum. 
Secondary  Changes. — None. 


Fig.  44.  Fig.  45.  Fig.  46. 

Fig.  44. — Dilaceration  of  a  mandibular  third  molar.      Occlusal  surface  show- 
ing convolutions  of  the  crown  with  pigmented  intervening  fissures. 
Pig.  45. — The  same.     Lingual  aspect. 
Fig.  46. — The  same.      Buccal  aspect. 

HISTOLOGY 

At  the  seat  of  injury  the  dentinal  tubules  pursue  a  course  which  is 
far  longer  than  normal.  They  are  also  strongly  curved.  The 
dentine  at  the  point  of  curvature  may  sometimes  exhibit  signs  of 
absorption  on  its  cortical  aspect,  with  subsequent  deposition  of 
cementum.  The  pulp  canal  retains  its  central  position.  The 
granular  layer  of  Tomes  is  highly  pronounced  and  thickened;  and 
cemental  hyperplasia,  a  result  of  chronic  inflammation  of  the  perio- 
dontal membrane,  is  present  (see  Fig.  48).  The  cementum  of 
the  parts  unafifected  by  traumatism  is  normal  and  devoid  of 
lacunae,  though  its  lamination  is  marked. 

In  dilaceration  of  the  cervical  region,  a  condition  less  common  than 
that  just  described,  the  amelo-dentinal  junction  is  bent  on  itself, 
and  at  times  exhibits  signs  of  absorption.  This  may  contain  hyper- 
plasia cementum  or  enamel.  The  latter  tissue  may  or  may  not  be 
normal  in  structure.  At  times,  however,  a  fissure  or  fissures,  or 
even  a  canal,  may  exist,  as  in  Fig.  39. 

(ii)  Gemination 

Definition. — The  union  of  two  or  more  teeth.  There  are  two  kinds 
of  gemination  {\)  True,   (ii)  False.     Of  these  "True"  gemination 


44 


THE   DENTAL   TISSUES 


is  the  term  applied  to  those  teeth  which  are  joined  to  one  another  by 
some  cause  which  operates  during  developmental  periods,  and 
without  the  aid  of  inflammatory  conditions  of  the  root  membrane, 
"False"  gemination  when  the  osteoblasts  of  the  root  membrane, 
as  a  result  of  productive  periostitis,  have  laid  down  an  overgrowth 


Fig.  47. — Dilaceration  of  the  cervical  region  of  a  human  incisor.  Prepared 
by  grinding.  Unstained.  Magnified  12  times,  e.  Normal  enamel;  i.  Involu- 
tion of  enamel  into  the  dentine  by  penetration  of  the  amelo-dentinal  junction, 
probably  the  result  of  absorption;  h.c.  Hyperplasic  cementum  at  seat  of  dilac- 
eration; s.c.  Normal  structureless  cementum;  d.  Dentine. 


of  the  cementum.  It  follows,  from  this  definition,  therefore,  that  in 
the  former,  enamel  and  dentine  may  generally  constitute  the  ma- 
terial which  unites  the  teeth,  while  in  the  latter  hyperplasic  ce- 
mentum is  the  bond  of  union.     As  a  rule  members  of  the  same 


PATHOLOGICAL   CONDITIONS    OF   THE    DENTINE 


45 


Fig.  48. — Dilaceration  of  the  radicular  region  of  a  human  canine.  A  second 
smaller  curvature,  not  shown  in  the  photomicrograph,  existed  near  the  apex  of 
the  tooth.  Prepared  by  grinding.  Unstained.  Magnified  15  times.  Shows 
enormous  thickening  of  the  hyperplasic  cementum.  d.  Dentine:  H.C.  Cemen- 
tum;  G.  Granular  layer  of  Tomes. 


46 


THE    DENTAL    TISSUES 


dentition  are  affected,  but  it  occasionally  happens,  as  will  be  pres- 
ently described,  that  individual  teeth  of  the  two  dentitions  are  con- 
cerned. Thus  a  sub  variety  of  "False"  gemination  may  be  known 
as  "Diphyodontic"  gemination. 

Etiology. — The  cause  of  the  first  variety  is  a  little  obscure.     It  may 
be  due  to  dichotomy  of  the  tooth  germ  at  an  early  period  of  evo- 


FiG.  49. — True  gemination  of  permanent  mandibular  incisors.  The  labial 
aspect  of  the  crown  was  excavated  to  ascertain  the  existence  of  one  common 
pulp  cavity. 

lution,  or  it  may  be  due  to  fusion  of  two  or  three  tooth  germs.  This 
commonly  occurs  in  a  parallel  direction;  but  not  always.  The  teeth 
may  be  joined  throughout  their  lengths,  wholly  or  partially. 

In  the  deciduous  series,  the  mandibular  incisors  and  canines 
are  most  frequently  geminated.  Thus  the  first  and  second  incisors 
(Fig.  52),  or  the  second  incisor  and  canine,  may  be  united,  or  more 


Fig.   50. — False  gemination  of  three  left  maxillary  molars. 

rarely  the  two  incisors  and  a  supernumerary  tooth  (Figs.  54,  55  and 
56).  In  the  permanent  dentition  supernumerary  teeth  are  often 
geminated  to  molars  or  incisors.  Fig.  53  shows  an  example  of  a, 
dwarfed  supernumerary  tooth  geminated  to  a  small  third  molar. 
It  is  a  genuine  case  of  true  gemination,  as  the  dentine  is  normal 
and  presents  no  signs  of  the  changes  observed  in  certain  odontomes. 
Fig.   50   shows  false  gemination   of   three   maxillary   molars^ — a 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE 


47 


somewhat  rare  condition.  False  gemination  is  due,  as  already- 
indicated,  to  an  overdevelopment  of  hyperplasic  cementum; — a  result 
of  productive  periostitis  of  contiguous  teeth.  The  bony  septa  have 
become  absorbed  and  a  solid  union  of  the  parts  results. 


Fig.   51. — False  gemination  of  maxillary  left  second  and  third  molars. 

Geminated  teeth  occasionally  occur  in  ovarian  teratomatous  cysts. 

Macroscopical  Appearances. — The  external  surfaces  are  irregular 

and  exhibit  considerable  thickening  over  the  region  of  the  roots, 


FI 


SI 


Fig.  52. — True  gemination  of  deciduous  mandibular  first  and  second  incisors. 
Coronal  section  of  the  teeth.  Prepared  by  grinding.  Unstained.  Magnified 
15  times.     F.I.   First  incisor;  s.i.  Second  incisor. 

in   the  case  of  "False"  gemination;   a  normal   contour,  with  no 
appreciable  addition  in  size,  obtains  in  "True"  gemination. 

Secondary  Changes. — Geminated  teeth  often  show  early  symptoms 
of  caries. 


48 


THE    DENTAL    TISSUES 


DS 


PM 


Fig.  53. — True  gemination  of  a  third  maxillary  human  molar  with  an  in- 
verted [impacted  conical  supernumerary  tooth,  as  described  in  the  text.  Pre- 
pared by  grinding.  Unstained.  Magnified  15  times.  R.  Pulp  canals  in  the 
extremely  divergent  roots  of  the  molar;  p.m.  Its  pulp  cavity;  d.s.  Dentine 
of  supernumerary  tooth;  P,S.  Its  pulp  cavity;  H.c.  Hyperplasic  cementum. 


PATHOLOGICAL   CONDITIONS    OF    THE   DENTINE  49 

HISTOLOGY 

The  diagrams  reproduced  in  Figs.  54,  55,  and  56  represent 
horizontal  sections  of  true  gemination  of  the  mandibular  deciduous 
first  and  second  incisors,  and  a  small  supernumerary  tooth,  and 
reveal  the  facts  that  near  the  cervical  margins  three  pulp  chambers, 
separate  and  distinct  from  each  other,  each  having  normal  radiating 
fine-tubed  dentine  exist.  The  enamel,  as  a  narrow  cervical  ring, 
surrounds  each  segment  of  the  tissue.  Lower  down  two  pulp 
chambers,  one  rounded  and  the  other  dumb-bell  shaped,  are  formed 
(Fig.  55).  The  dentine,  normal  in  every  particular,  intervenes 
between  the  pulp  cavities.  A  section  near  the  apex  of  the  root  shows 
that  the  two  pulp  cavities  have  become  merged  into  one.  In  every 
instance   the   dentine   and   cementum   are   unaffected   by   morbid 


Fig.  54.  Fig.  55.  Fig.  56. 

Fig.  54. — Horizontal  section  of  three  geminated  teeth  at  cervical  region,  where 
there  are  three  pulp  chambers. 

Fig.  55. — The  same,  showing  two  root  canals. 
Fig.  56. — The  same,  showing  one  root  canal. 


changes,  the  latter  being  merely  a  very  attenuated  annular  layer  of 
solid  osseous  material. 

In  Fig.  53  there  is  a  strong  suggestion  of  the  impaction  of  a 
supernumerary  tooth  in  the  midst  of  the  third  molar  producing  a 
cleavage  of  the  tooth  germ.  It  is  a  curious  anomalous  condition, 
and  probably  unique. 

The  dentine  exhibits  the  usual  characteristics,  but  the  enamel 
has  been  removed  in  process  of  grinding  the  specimen,  while  the 
cementum  is  hyperplasic,  indicating,  no  doubt,  that  an  injury  had 
been  received  by  the  immature  tooth  germ.  Embracing  the  neck 
of  the  supernumerary  tooth  the  cementum  of  the  molar  is  continued 
outwards,  on  one  side  as  a  fine  triangular  peninsula  of  hard  tissue, 
on  the  other  as  a  rounded  cone-like  elevation. 

The  root  canals  of  the  molar  can  be  clearly  followed  almost  to  the 
apices  of  these  cemental  and  dentinal  projections. 


50 


THE   DENTAL   TISSUES 


Diphyodontic  Gemination 

There  have  recently  come  into  the  possession  of  the  author  two 
examples  of  this  condition,  in  which,  as  already  stated,  a  deciduous 
tooth  may  become  firmly  united  to  a  member  of  the  permanent 
series.  The  first,  [which  has  no  available  history],  illustrated  in 
Figs.  57  and  58,  is  a  left  maxillary  first  incisor  removed  from  the 


Fig.  57.  Fig.  58.  Fig.  59. 

Fig.  57. — Diphyodontic  gemination  of  a  maxillary  left  permanent  first  incisor. 
Labial  aspect. 

Fig.  58. — Diphyodontic  gemination.  Same  specimen  as  preceding.  Mesial 
aspect. 

Fig.  59. — Mandibular  left  permanent  second  incisor  affected  by  diphyodontic 
gemination.     Labial  aspect. 

mouth  of  a  child  of  ten  or  eleven  years  old.  The  labial  surface  measures 
18  mm.  in  length,  it  is  9  mm.  wide,  the  normal  measurements  of  a  simi- 
lar tooth  being  12.5  mm.  and  9  mm.  respectively.  The  mesial 
surface  of  the  root  is  7  mm.  the  distal  6  mm.  in  extent.  The  root 
was  deflected  toward  the  mid-line,  its  apex  was  still  patent.     The 


Fig.  60.  Fig.  61.  Fig. 

Fig.  60. — Similar  to  preceding. 
Fig.  61. — Similar  to  preceding. 
Fig.  62. — Similar  to  preceding. 
Fig.   63. — Similar  to  preceding. 


62.  Fig. 

Lingual  aspect. 
Distal  surface. 
Mesial  surface. 
Occlusal  surface. 


63- 


length  of  the  deciduous  attached  crown  measured  10  mm.,  its  width 
6  mm. 

The  second  case  for  which  the  author  is  indebted  to  Dr.  Edward 
C.  Kirk,  occurred  in  the  mouth  of  a  girl  aged  fourteen  years.  It  is 
a  left  mandibular  second  incisor.  It  was  said  to  have  erupted  at  the 
eighth  year,  and,  so  the  patient  affirms,  followed  a  deciduous  prede- 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  5 1 

cessor.  Its  position  and  shape  were  annoying,  as  the  incisive 
edge  was  directed  toward  the  lower  Up.  On  examination,  the 
tooth  was  firmly  socketted,  although  it  was  denuded  of  soft  tissue 
on  its  labial  aspect.  The  bone  in  this  situation  had  been  absorbed 
completely,  and  the  gingival  tissue  was  inflamed.  The  periodontal 
attachment  on  the  mesial,  distal  and  lingual  sides  was  normal.  The 
other  teeth  were  normal,  and  there  was  no  purulent  effusion  around 
them  (see  Figs.  59,  60,  61,  62  and  63). 

The  general  appearances  of  these  geminated  teeth  are  shown  in 
the  photographs.  The  length  of  the  whole  tooth  was  16  mm., 
its  greatest  width  3  mm.  The  width  of  the  attached  deciduous 
crown  measured  6  mm.  The  length  of  the  root  itself  was  10  mm. 
and  it  was  divided  longitudinally  by  an  extensive  fissure  on  both 
aspects.  The  crown  of  the  deciduous  tooth  was  placed  at  right 
angles  to  that  of  the  permanent  tooth,  its  concave  hngual  surface 
directed  upward  and  its  labial  convex  surface  downwards. 

(iii)  Lacunar  and  other  Defects 

Definition. — Irregular  spaces— not  of  an  interglobular  nature — 
which  admit  of  no  classification,  found  in  the  substance  of  the 
dentine. 

Etiology. — Congenital  defective  nutrition  or  perverted  metabo- 
lism of  the  pulp  cells. 

HISTOLOGY 

Dentz,  of  Utrecht,  has  observed  in  the  early-erupted  teeth  of  a 
newly-born  child  certain  curious  defects,  which  are  undoubtedly 
congenital  in  origin.  Bodies  containing  apparently  six  or  eight 
nucleated  cells,  which  were  closely  applied  to  each  other  and  some- 
what resembling  Pacinian  corpuscles  were  discovered  in  the  dentine, 
which  measured  about  0.25  mm.  near  the  amelo-dentinal  junction. 
The  spaces  were  of  great  size  (125/x  in  length),  oval  or  bilobed  in 
shape  and  outline  (Fig.  64).  A  spiral  structure,  which  might  be 
in  continuity  with  the  dentinal  fibrils  could,  with  difficulty,  be 
made  out.  It  is  possible  that  these  defects  marked  a  stage  in  the 
formation  of  interglobular  spaces. 

Ovarian  teeth  sometimes  show  areas  of  dentine  where  the  tissue 
has  undergone  considerable  metamorphosis.  In  Fig.  65  the  tubes, 
which  are  very  much  smaller  than  those  of  the  rest  of  the  dentine 
are  running  centripetally,  not  centrifugally,  from  a  point  centred  at 


52 


THE   DENTAL   TISSUES 


Fig.  64. — Lacunar    defects    in    dentine.      (Dentz's    specimen.     Photomicrograph 
by  Howard  Mtcmmery.)    - 


DD 


Fig.  65. — Coronal  section  of  a  tooth  removed  from  a  teratomatous  ovarian 
cyst.  Prepared  by  grinding.  Unstained.  Magnified  15  times,  e.  Pigmented 
enamel  of  def ective_quality ;  d.   Dentine;  d.d.   Developmental  defects  in  dentine. 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE 


53 


the  amelo-dentinal  junction,  below  the  sulcus  of  the  crown 'which 
intervenes  between  the  two  deformed  cusps.  In  colour  the  abnor- 
mal patch  resembles  a  pale  brown,  similar  to  that  of  the  enamel. 
The  foundations  of  the  irregularity  seem  to  be  matrix  of  a  poor 
quality,  myriads  of  tiny  interglobular  spaces  apparently  covering 
it  through  all  its  extent.  It  bears  some  resemblance  in  outline  to  a 
sheaf  of  wheat. 

The  normal  dentinal  tubes  are  interrupted  in  their  courses, 
which,  however,  are  resumed  in  the  immediate  neighbourhood 
of  the  enamel. 


D  D 


Fig.  66. — Structural  defect  in  human  dentine.  Prepared  as  in  the  preceding 
figure.  Magnified  40  times,  e.  Enamel;  D.  Normal  dentine;  d.d.  Develop- 
mental defect. 

The  periphery  of  this  interesting  structure  displays  signs  of 
lacunar  absorption  of  the  healthy  tissue,  while  two  or  three  large 
spaces,  filled  with  amorphous  material,  occupy  the  position  of  the 
amelo-dentinal  junction.  The  enamel  itself  is  slightly  defective 
in  structure. 

(iv)  Congenital  Pigmentation 

Definition. — ^Deep  brown  coloration  of  the  dentinal  matrix  and 
contiguous  cementum  of  sound  {i.e.,  non-carious)  teeth. 


54  THE   DENTAL   TISSUES 

Etiology. — Some  obscure  congenital  defect. 

Macroscopical  Appearances. — When  a  congenitally  pigmented 
tooth  is  cracked  in  the  jaws  of  a  strong  vice,  its  deeply  pigmented 
characters  are  seen.  The  staining  is  uniform,  not  as  in  Patho- 
logical pigmentation,  as  described  on  p.  76,  confined  to  one  part 
entirely,  or  more  pronounced  in  any  particular  locality. 

The  microscopical  examination  reveals  nothing  except  pigment- 
ation of  the  matrix. 

(v)  Nanoid  or  Dwarfed  Dentine 

Definition. — Aplasia  or  agenesia  of  the  dentine  of  unerupted 
teeth,  especially  of  their  roots.  It  is  not  a  simple  atrophy  of  the 
parts.  Atrophy  implies  a  retrogressive  metamorphosis  occurring 
in  tissues  or  organs  which  were  originally  well  formed  or  "in  pro- 


FiG.  67.  Fig.  68. 

Fig.    67. —  Maxillary  left    first  permanent   incisor   showing   nanoid   dentine. 
Labial  aspect. 

Fig.  68. — Same  as  the  preceding.     Lingual  aspect. 

portion  to  the  age  of  the  organism  well  grown. ""^  Such  a  variation 
leads  to  diminution  in  size  of  the  organ  or  structure.  While  the 
constituent  parts  shrink  variously,  through  decrease  in  number  and 
size^  there  is  no  marked  alteration  in  the  minute  anatomy  or  in 
chemical  composition. 

Etiology. — ^An  actual  immature  condition  or  imperfect  develop- 
ment of  the  roots  of  teeth  may  be  due  to  the  fact  that  for  some 
unknown  reason,  teeth  have  been  made  to  assume  abnormal  posi- 
tions in  their  crypts  in  the  alveolar  process  of  the  jaws — positions 
in  which  eruption  is  impossible.  The  growth  of  the  roots  not  being 
required  to  aid  and  complete  this  physiological  process  may  suddenly 
cease.  Failure  of  eruption  is  caused  by  failure  of  root  formation, 
or  perhaps  per  contra.  The  condition  occurs  in  the  young — about 
fifteen  years.  The  maxillary  incisors  may  be  affected,  in  which  case, 
if  the  alveolar  process  in  the  neighbourhood  of  the  colnmna  naris 
is  dense  and  prominent,  nanoid  teeth  may  be  suspected.  A  skia- 
gram will  reveal  the  condition. 

1  Hektoen  &  Riesman,  "A  Text-book  of  Pathology,"  Vol.  i,  1901. 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  $5 

Macroscopical  Appearances. — In  the  case  figured,  the  actual 
measurements  of  the  crown  were  13  mm.  in  length.  The  root  was 
3.2  mm.  on  its  labial,  6.1  mm.  on  its  lingual  aspect.  The  apical 
foramen  was  closed  and  the  pulp  canal  shortened  by  about  one-third 
of  the  length  of  the  whole  tooth.  The  proper  length  of  the  root 
should  have  been  20  mm.  or  more.  The  microscopical  structure 
of  nanoid  dentine  calls  for  no  remark. 

(vi)   Vascular  Canals 

Definition. — ^Large,  uniformly  sized  channels  in  the  tissue  passing 
from  cementum  to  pulp,  and  containing,  post  mortem,  a  thrombosed 
blood-vessel. 

Etiology. — -The  persistence  at  the  periphery  of  the  pulp  of  a  large 
vessel  or  bundle  of  capillaries  would  probably  give  rise  to  this 
abnormality. 

Vascular  canals  are  occasionally  associated  with  dilaceration 
of  the  teeth. 

HISTOLOGY 

Running  from  the  pulp  to  the  periphery,  and  piercing  both  dentine 
and  cementum,  the  channels  pass,  sometimes  sending  out  a  branch 
or  tributary  which  may  end  in  a  cul-de-sac.  But  the  termination 
of  the  main  canal  itself  is  on  the  inner  surface  of  the  periodontal 
membrane. 

A  small  artery  with  its  attendant  vein  may  be  found  in  situ, 
the  former  empty  of  its  contents,  the  latter  sometimes  blocked  by 
means  of  a  thrombus. 

The  condition  is  unconnected  with  cemental  hyperplasia,  or  any 
of  those  pathological  changes  which  sometimes  occur  round  and 
about  the  pulp  canals. 

The  presence  of  vascular  canals  in  the  hard  tissues  of  the  roots 
of  teeth  constitutes  a  grave  source  of  danger  if  some  devitalising 
agents  happen  to  be  used  in  connection  with  diseases  of  the  pulps 
of  teeth  so  affected.  The  condition  cannot  be  diagnosed  till  after 
the  removal  of  the  tooth. 

B. — ACQUIRED   DISEASES 

(vii)  Absorption 

This  common  pathological  condition  may  take  place  from  without 
or  from  within,  i.e.,  from  the  cemental  or  the  pulp  side. 


56 


THE    DENTAL    TISSUES 


Definition. — The  removal  of  dentine,  as  part  of  a  pathological 
process — in  contradistinction  to  the  physiological  absorption  of 
roots  of  deciduous  teeth — not  due  to  caries. 

Etiology. — Chronic  inflammation  of  the  pulp  or  periodontal 
membrane  from  whatsoever  cause  may  induce  certain  changes 
in  the  cells  of  the  soft  tissues,  which,  unduly  stimulated,  remove 
the  hard  parts  in  their  immediate  proximity.  The  absorption  is 
probably  due  (i)  to  the  activities  of  multi-nucleated  giant  cells 
(osteoclasts)  as  physiological  factors,  because  these  bodies,  although 


CH 


Pig.  69. — External  absorption  of  dentine.  Shows  d.  Dentine;  s.c.  Normal 
structureless  cementum;  h.c.  Hyperplasia  cementum.  {From  a  section  in  the 
collection  of  A.  W.  W.  Baker.) 

they  have  never  been  observed  in  the  pulp  tissue,  nor  do  they  exist 
in  the  inner  aspects  of  the  periodontal  membrane,  yet  are  common 
enough  in  the  bay-like  recesses  of  the  alveolar  bone.  The  absorption 
may  also,  most  probably,  be  correctly  ascribed  (ii)  to  the  presence 
of  absorption-leucocytes  or  phagocytes  brought  into  physiological 
contact  with  the  hard  parts  by  means  of  the  small  cell  infiltration 
of  the  soft  tissues,  the  result  of  the  inflammation. 

Acute  inflammation  of  the  periodontal  membrane  accompanied 
by  suppuration,  as  a  result  of  impaction  of  a  contiguous  tooth  may 
also  induce  absorption,  probably  (iii)  by  the  action  of  acid  pus 
merely  dissolving  away  the  lime  salts  from   the  organic  matrix 


PATHOLOGICAL  CONDITIONS  OF  THE  DENTINE       57 

near  the  seat  of  lesion,  a  pathological  action  resembling  that  which 
occurs  sometimes  in  absorption  of  bone  viz.,  halisteresis. 

Pathologists  agree  that  in  the  case  of  bone,  pathological  absorp- 
tion is  produced,  either  by  (a)  the  agency  of  osteoclasts  ("lacunar 
absorption");  (b)  decalcification  ("halisteresis");  or  (c)  granulation 
tissue,  through  the  medium  of  certain"  round  cells  which  possess  a 
phagocytic  function.  It  is  exceedingly  likely  that  these,  or  similar 
agencies,  can  produce  like  results  with  regard  to  the  absorption 
of  cementum  and  dentine. 

Macroscopical  Appearances. — When  the  apex  or  side  of  the  root 
is  affected,  a  roughening  of  the  surface  results.  Thus  "needle- 
point" absorption  is  common  on  the  apex  of  the  root. 

No  pigmentation  occurs,  and  no  caries. 

Secondary  Changes. — If  the  inflammation  undergoes  resolution, 
which  it  most  generally  does,  organisation  supervenes  on  an  attack 
of  chronic  inflammation,  and  the  cementum,  more  or  less  lacunated 
and  laminated  on  the  one  hand,  or  a  cementum-like  substance,  which 
has  been  termed  "  osteodentine  " — a  bad  appellation — or  even  bone, 
well-organised  and  unmistakable — on  the  other  hand,  may  be 
produced. 

HISTOLOGY 

(a)  External  Absorption 

In  the  belief  that  osteoclasts  properly  so  constituted  do  not  exist 
in  the  pulp  or  the  innermost  zone  of  the  root  membrane,  it  is  not 
surprising  to  find  absence  of  Howship's  foveolae.  It  is  true  that 
more  or  less  festooned  outhnes  are  met  with  in  places,  but  they  are 
nothing  like  those  found  in  the  physiological  absorption  organ  of 
deciduous  teeth  or  on  the  surface  of  the  shafts  of  bone. 

In  this  way,  therefore,  in  the  case  of  external  absorption,  a  por- 
tion of  the  external  surface  of  the  dentine  loses  its  normal;  outhne, 
a  break  occurs  in  its  continuity,  the  breach  of  surface  being  filled 
with  irregularly-developed  cementum.  It  may  be  hollowed  out 
sometimes  to  any  depth,  or  it  may  be  absorbed  in  a  straight  hne, 
as  in  a  specimen  of  Baker's,  of  Dublin  (Fig.  69). 

Specimens  of  the  first  condition  show  the  following  details:  The 
normal  cementum  and  granular  layer  have  disappeared;  no  sharp 
line  of  demarcation  intervenes  between  the  normal  and  the  diseased 
parts;  the  dentinal  tubes  are  cut  off  squarely  with  their  course,  and 
— a  point  of  some  interest — cemental  lacunae,  large  and  confluent. 


58  THE    DENTAL    TISSUES 

and  not  possessing  prominent  canaliculi  are  placed,  in  no  great 
numbers,  immediately  on  the  cut  ends  of  the  tubes.  Many  la- 
cunae are  of  the  abrachiate  variety. 

Both  kinds  of  absorption  may  be  illustrated  by  Dr.  A.  W.  W. 
Baker's  example.  He  describes  it  by  saying'^  that  "two-thirds  of 
the  circumference  of  the  tooth  show  evidence  of  inflammatory 
action  of  a  more  or  less  chronic  nature,  that  is  to  say,  there  can  be 
traced  zones  of  the  cementum  where  the  root  membrane  was  in  a 
healthy  condition  and  deposited  normal  cementum,  then  periods 
where  the  root  membrane  became  actively  inflamed  and  absorption 

took  place The    remaining    third    of    the    circumference 

of  the  root  showed  absorption  by  abscess  of  a  severe  and  extensive 
nature,  as  not  only  the  cementum  but  also  the  dentine  was  involved 

and   absorbed The    distinct  band  of  new  tissue  is  here 

very  well  marked,  and  at  first  sight  seems  as  if  the  section  were  folded 
upon  itself"  (see  Fig.  69). 

The  writer  considers  that  in  this  case  osteoclasts  are  the  predomi- 
nating factors  of  the  absorption.  Sir  John  Bland-Sutton,  in  his 
"Introduction  to  General  Pathology,"  p.  124,  1887,  says:  "In  the 
giant  cells  (formed  by  the  fusion  of  leucocytes,  which  have  migrated 
from  the  new  capillary  blood-vessels  of  the  granulation  tissue  of 
inflammation)  we  have  the  counterpart  of  the  fusion  of  phagocytes; 
the  large  multinuclear  osteoclasts  seen  in  places  where  vertebrate 
bones  and  teeth  are  undergoing  absorption,  must  also  be  placed  in 
the  same  category." 

If  this  interpretation  is  correct  (and  modern  research  would 
seem  to  confirm  it),  it  is  not  difficult,  it  must  be  confessed,  to  com- 
prehend not  only  how  the  new  formation  of  osteoblasts  in  the  mem- 
branes bordering  the  periphery  of  the  cementum  arises,  but  also  in 
what  manner  their  transformation  into  osteoclasts,  and  ultimately 
lacunar  corpuscles,  is  brought  about. 

G.  V.  Black  {op.  cit.),  speaking  of  absorption,  states  his  opinion 
that  the  physiological  absorption  of  deciduous  teeth  is  precisely 
the  same  plan  by  which  the  roots  of  permanent  teeth  are  occasion- 
ally, pathologically  absorbed,  either  in  part  or  completely.  Never- 
theless, though  this  writer  evidently  believes  that  cementum  and 
dentine  are  both  absorbed  by  means  of  osteoclasts,  nowhere  does 
he  make  a  definite  statement  to  that  effect,  nor  do  his  figures  show 
them.     Indeed,  while  in  every  case  his  drawings  of  absorbed  den- 

1  "Advanced  and  Retarded  Dentition."  Journal  British  Dental  Association, 
p.  432,  1902. 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  59 

tine  and  cementum  exhibit  outlines  somewhat  simulating  those  of 
the  foveolje  of  Howship,  he  is  careful  to  avoid  the  pictorial  expres- 
sion of  an  osteoclast — or,  as  some  would  call  it,  a  cementoclast — 
filling  up  the  excavations.  One  illustration  exhibits  particularly 
well  these  giant  cells  on  the  alveolar  side  of  the  root  membrane, 
but  they  are  omitted  on  the  other.    . 

Unique  Extensive  Absorption 

A  singularly  instructive  case  of  the  absorption  of  the  roots  of 
many  of  the  permanent  teeth  in  one  mouth  which  came  under  the 
personal  notice  of  the  author  may  be  quoted.  The  case  is  possibly 
unique;  and,  possessing  very  extraordinary  characteristics,  its 
aetiology  is  so  difiiciilt  to  determine,  and  the  actual  pathological 
phenomena  which  it  exhibits  so  full  of  significance,  that,  as  a 
result,  it  is  raised  to  a  high  level  of  interest  and  importance. 

A  man  aged  44,  has  been  under  observation  for  a  number  of  years, 
his  mouth  presenting  very  varied  aspects  as  an  infection  advanced. 
Family  History:  The  mother  is  edentulous:  the  father  practically 
so.  A  sister,  aged  25,  has  the  right  maxillary  canine  still  unerupted, 
the  cusp  just  appearing  through  the  gum.  There  is  no  purulent 
effusion  round  her  teeth.  Past  History:  For  fourteen  years  the  patient, 
then  being  aged  about  29-30,  had  a  swelling  under  the  mandibular 
first  molar,  which  was  very  carious.  Extraction  under  an  anaes- 
thetic failed  to  remove  the  tooth  entirely.  On  examining  the  mouth 
at  the  time  of  operation,  it  was  discovered  that  all  the  other  molars — • 
the  upper  and  lower  third  molars  not  included — had  their  crowns 
only  slightly  erupting  through  the  gum,  although  the  premolars 
and  incisors  were  fully  developed  and  occluded  in  a  normal  manner. 
As  the  conditions  were  extremely  uncommon,  and  as  the  swelling 
"  did  not  go  down,"  the  patient  was  sent  to  the  consulting  surgeon  of 
a  Hospital,  who,  anxious  to  await  further  developments  and  give 
Nature  an  opportunity  of  correcting  the  abnormal  state  of  the  mouth 
and  jaws,  merely  ordered  an  "ointment"  for  external  use. 

When  the  dental  surgeon  next  saw  the  case  an  abscess  had  opened 
which  would  not  heal.  The  patient  was  thereupon  sent  to  the 
Hospital,  and  the  surgeon  for  the  day  endeavoured  to  remove  the 
roots  of.jthe  tooth,  but  failed.  He  was  then  seen  by  the  dental 
surgeon^of  another  Hospital,  and  again  operated  upon,  but  with  no 
greater  success.  Some  long  time  afterwards  the  patient  told  his 
private'-'practitioner  that  a  piece  of  bone,  or  "something  like  it," 


6o  THE    DENTAL   TISSUES 

came  through  the  opening  on  the  face,  and  then  the  abscess  healed. 
All  the  partially-erupted  molars  except  one  have  been  shed  spon- 
taneously— i.e.,  become  loose,  and  been  removed  from  the  mouth 
by  means  of  the  fingers,  and  are  in  a  more  or  less  similar  condition, 
showing  signs  of  extensive  absorption.  The  crown  of  a  third  right 
maxillary  molar  was,  in  December,  1908,  felt  with  an  explorer, 
buried  in  the  jaw,  the  tooth  itself  erupting  and  spontaneously 
becoming  shed  by  absorption  of  its  roots,  six  months  later. 

The  patient  himself  told  the  author  that,  with  jaws  closed,  the 
fingers  could  be  inserted  between  the  occlusal  surfaces  of  the  molar 
teeth  on  both  sides,  showing  that  they  never  occluded  in  the  normal 
manner,  a  space  of  one-sixteenth  or  one-thirty-second  part  of  an 
inch  intervening.  For  fifteen  months  there  had  been  a  certain 
amount  of  discharge  of  pus  and  swelling  of  the  gingival  tissues. 
Trismus  was  present  at  times  to  a  slight  degree,  and  the  patient  also 
suffered  greatly  from  insomnia.  The  maxillary  right  canine  was 
sound,  but  had  an  abscess  associated  with  it,  and  was  therefore  some- 
what loose.  Having  meanwhile  been  crowned,  it  is  now  quite  firm. 
Practically  there  has  been  no  pain  throughout  the  whole  course  of 
the  disease,  the  discharge  of  pus  from  the  back  of  the  mouth  being 
the  most  prominent  symptom.  There  has  been  no  tartar  to  speak 
of,  and  the  general  condition  of  the  oral  mucous  membrane  is,  and 
has  been,  fairly  good.  The  patient  had  rheumatic  fever  when  he 
was  aged  33,  is  somewhat  delicate,  and  probably  neurasthenic. 

At  the  time  of  examination  it  was  noted  that  the  mouth  is  clean 
and  well  cared  for.  Tartar  is  absent  round  the  necks  of  the  remain- 
ing teeth.  Great  absorption  of  the  alveolar  processes  has  occurred. 
Of  all  the  maxillary  teeth,  the  two  canines,  the  second  left  premolar, 
and  the  root  of  the  second  right  premolar  remain,  one  of  the  former 
having  been  crowned.  The  latter,  however,  shows  signs  of  chronic 
inflammation  of  the  periodontal  membrane  especially  on  its  dis- 
tal aspect,  probably  through  loss  of  bone-substance  of  the  jaw. 
The  mandibular  alveolar  ridges  are  flat;  the  teeth  remaining  in 
situ  are  the  two  second  incisors,  the  canines,  the  two  first  pre- 
molars, and  the  left  second  premolar.  The  other  teeth  have  been 
extracted  from  time  to  time,  through  loosening  on  account  of  the 
alveolar  changes.  Eruption  of  the  right  mandibular  third  molar- 
is  now  taking  place. 

Macroscopical  Appearances. — (i)  Left  mandibular  second  molar: 
On  the  occlusal  surface  of  the  crown  there  is  a  rounded  cavity  occu- 
pying the  site  of  the  postero-mesial  cusp,  its  greatest  diameter  being 


PATHOLOGICAL   CONDITIONS    OF   THE   DENTINE  6 1 

4.5  mm.  and  shortest  3.5  mm.  Extending  downwards  and  back- 
wards and  towards  the  lingual  side,  it  avoids  the  pulp  chamber  and 
opens  externally  below  the  cervical  margin  on  the  posterior  surface, 
by  a  small  pin's  head  point,  on  the  lingual  surface  by  two  sinuous 
perforations  (Fig.  70),  and  in  the  radicular  region  in  a  large  irregular 
shallow  excavation,  9.5  mm.  in  length.  The  greatest  area  of  ab- 
sorption is  found  on  the  mesial  aspect  (Fig.  71).     Here  the  enamel  is 


V 

Fig.  70.  Fig.  71. 

Fig.  70. — Left  mandibular  second  molar:  lingual  aspect. 
Fig.   71. — The  same  tooth:  mesial  aspect. 

unaffected,  but  immediately  below,  a  large  loss  of  dentine  and  ce- 
mentum  has  taken  place,  measuring  12  mm.  long  by  8  mm.  wide. 
The  cementum  is  hyperplasic,  the  pulp  cavity  not  exposed.  The 
length  of  the  tooth  is  21  mm.  There  is  no  transparency  of  the  roots, 
which  -  are  confluent  through  the  hyperplasia  of  the  cementum. 
Qneminute  apical  foramen  can  be  detected. 


Fig.  72.  Fig.  73. 

Fig.   72. — Right  maxillary  third  molar:  distal  aspect. 
Fig.  73. — The  same  tooth:  buccal  aspect. 

(ii)  Right  maxillary  third  molar:  The  crown  is  flattened  antero- 
posteriorly .  A  large  amalgam  filling,  situated  on  the  buccal  surface, 
fills  the  site  of  the  antero-external  and  antero-internal  cusps.  A 
discoloured  patch  of  enamel  is  seen  on  the  free  edge.  The  mesial 
surface  of  the  root  is  discoloured  and  presents  three  small  hollows. 
A  large  area  of  absorption  is  observed  on  the  distal  and  buccal 
surfaces  (Figs.  72  and  73),  the  former  being  entirely  excavated  ex- 
cept at  the  extreme  apical  region.     The  roots  are  very  hyperplasic 


62  THE    DENTAL    TISSUES      ' 

and  reflected  backwards.  The  apical  foramina  are  closed  and  invisi- 
ble. The  whole  of  the  palatine  root  has  disappeared,  the  consumed 
surface  measuring  12  mm.  by  6  mm.  by  5  mm.  The  length  of  the 
tooth  is  21  mm. 

(iii)  Right  maxillary  second  molar:  The  crown  is  roughly  quadri- 
lateral in  shape.  There  is  a  gold  filling  on  the  morsal  surface  at 
the  part  between  the  antero-external  cusp  and  the  ridge  joining 
the  antero-internal  and  postero-external  cusps.  The  crown  is 
otherwise  free  from  caries.  The  buccal  roots  are  united  together, 
rough,  and  greatly  enlarged  by  hyperplasic  cementum,  the  surface 
being  very  slightly  attacked  by  the  destructive  process.  The  apical 
foramina  are  invisible.  The  palatine  root  is  largely  reduced  in 
length  by  the  absorption,  slightly  near  the  cervical  region  on  the 


Fig.   74.  Fig.  75. 

Fig.   74. — Right  maxillary  second  molar:  distal  aspect. 
Fig.   75. — The  same  tooth:  lingual  aspect.  , 

lingual  aspect,  more  so  at  the  apical  portion.  The  length  of  the 
tooth  to  the  apices  of  the  buccal  roots  is  18  mm.,  the  palatine 
root  measuring  16  mm.  (Figs.  74  and  75). 

(iv)  Left  maxillary  second  molar:  The  crown  is  non-carious.  There 
is  a  tendency  for  it  to  become  oblique  in  outline,  its  fissures  and  pits 
being  pronounced.  The  enamel  is  entirely  free  from  disease.  The 
buccal  roots  are  confluent,  but  discoloured.  There  are  cavernous 
openings  on  all  the  surfaces,  the  greatest  being  over  the  outermost. 
It  covers  an  area  of  42  sq.  mm.  (Fig.  77).  The  pulp  is  not  pene- 
trated. The  palatine  root,  exceedingly  honeycombed,  is  reduced  in 
length.  There  are  several  excrescences  of  hyperplasic  cementum  on 
the  distal  surface  of  the  body  of  the  tooth,  at  the  junction  of  the 
roots  (Fig.  76).  The  length  of  the  tooth,  on  its  buccal  aspect,  is 
20.5  mm.,  and  17.5  mm.  on  lingual  side. 

(v)  Left  maxillary  third  molar:  The  crown  here  is  non-carious, 
but  flattened  from  before  backwards.  Enamel,  while  being  dis- 
coloured, is  intact,  except  undergoing  a  small  amount  of  loss  on  the 
mesio-lingual  side.     Two  small  deep  pits  are  observed  on  the  buccal 


PATHOLOGICAL   CONDITIONS    OF    THE    DENTINE  63 

aspect.  All  three  roots  are  united  and  thickened.  The  buccal 
roots  on  the  free  surface  exhibit  an  absorption  area  7  mm.  and  4  mm. 
across  the  widest  and  narrowest  diameters  respectively,  while  dis- 
tally,  an  irregularly  formed  cavity  is  seen,  and  mesially,  two  small 
depressions,  closely  situated.  The  palatine  root  displays  the  rav- 
ages of  the  disease  best  of  all.  On  the  mesial  aspect  the  dentine  and 
pementum,  covering  a  superficies  of  13  mm.  by  7.5  mm.,  have  been 


Fig.  76.  Fig.  77. 

Fig.   76. — Left  maxillary  second  molar:  distal  aspect. 
Fig.   77. — The  same  tooth:  buccal  aspect. 

removed   (Fig.   79).     The  pulp  is  here  apparently  invaded.     The 
length  of  the  tooth  averages  19.5  mm. 

The  edges  of  the  excavations  of  all  the  teeth,  on  examination  with 
a  lens,  are,  generally  speaking,  rounded,  everted,  and  smooth  when 
dentine  and  cementum  are  destroyed;  when  enamel  is  involved, 
sharp  and  well  defined.     They  nowhere  exhibit  the  naked-eye  ap- 


FiG.  78.'  Fig.  79. 

Fig.    78. — Left  maxillary  third  molar:  mesio-lingual  aspect. 
Fig.   79. — The  same  tooth:  mesial  aspect. 

cearances  of  having  been  produced  by  osteoclasts,  as  Howship's 
foveolae  are  probably  entirely  wanting. 

In  reference  to  the  present  case  several  facts  stand  out  strikingly. 
First,  the  molars  erupted  most  imperfectly.  Some  unknown  rea- 
son lies  at  the  back  of  this.  The  ordinary  physiological  forces 
were  not  only  retarded  but  in  abeyance.  They  cannot  have  been 
affected   by   the   deciduous   dentition,   as   the   permanent   molars, 


64  THE   DENTAL   TISSUES 

of  course,  come  up  behind  the  milk  teeth.  There  must  be  some  con- 
stitutional disturbance  at  work,  acting  in  an  extraordinary  manner, 
in  producing  this  grave  defect  in  the  assumption  of  their  normal 
position  in  the  dental  arch  of  the  masticatory  organs.  The  history 
of  the  right  maxillary  third  molar  shows  that  its  life  duration  only 
extended  over  about  seven  or  eight  months.  There  is  complete 
absence  of  any  of  the  usual  causes  of  delayed  or  anomalous  eruption 
of  teeth,  and  its  cause  in  the  present  case  remains  a  mystery.  Sec- 
ondly, the  molars  were  not  devitalized — i.  e., "  dead,"  In  each,  except 
one,  the  pulp  was  alive  and  protected  by  its  wonderful  physiological 
resistance  from  the  attacks  of  the  great  pathological  processes 
going  on  outside.  Thirdly,  the  disease,  whatever  was  its  nature, 
was  practically  confined  to  the  molar  region.  None  of  the  other 
teeth  were  similarly  affected.  This  is  the  most  inexplicable  part 
of  the  case.  That  the  infection,  if  it  was  induced  by  pyogenic 
micro-organisms  in  the  first  place,  should  limit  itself  to  the  posterior 
parts  of  the  oral  cavity  is  truly  surprising.  Fourthly,  the  presence  of 
pus  in  large  quantities  at  times  was  a  prominent  sign  and,  no  doubt, 
associated  with  the  granulation  tissue  produced  around  the  roots 
of  the  teeth.  Fifthly,  the  molars,  having  shared  a  common  affec- 
tion which  was  spread  over  a  considerable  number  of  years,  be- 
came shed  spontaneously. 

It  is  difficult,  as  has  already  been  pointed  out,  to  decide  on  the 
aetiology  of  this  absorption.  The  author  puts  forward  his  opinion 
as  follows:  There  were  two  factors  probably  which  played  an  im- 
portant predisposing  part  in  the  production  of  the  disease — viz., 
(i)  the  disuse  of  the  teeth  through  lack  of  occlusion,  and  (2)  consti- 
tutional debility.  The  probable  sequence  of  events  would  be,  a 
bacterial  invasion  of  the  periodontal  membranes  of  the  functionless 
molars,  setting  up  a  chronic  periostitis  which  resulted  in  organiza- 
tion and  hyperplasia  of  the  cementum.  The  bacterial  influences 
not  having  been  withdrawn,  the  chronic  periostitis  was  further 
changed  into  granulation  tissue  which,  occupying  the  sockets  of 
the  teeth,  by  means  of  small  round  cells  possessing  phagocytic 
properties,  removed  not  only  the  alveolar  bone  but  almost  equally 
the  dentine  and  cementum  of  the  teeth, 

((8)  Internal  Absorption 

There  are  evidences  in  absorption  from  the  pulp  side  that  ab- 
sorption-leucocytes (osteoclasts)  perform  the  functions  of  removal 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  65 

of  the  dentine,  and  traces  of  the  effects  of  chronic  inflammation 
of  the  pulp  are  not  wanting.  Internal  absorption  is  accompanied 
by  obliteration  of  the  original  outline  of  the  root  canal,  the  resulting 
cavity  being  irregular  in  contour  and  enlarged  to  a  varying  degree. 
The  more  or  less  semilunar  excavations  may  be  confined  to  one  or 
more  portions  of  it,  and  produce  subsidiary  canals  which  run  at 
angles — acute,  right,  or  even  obtuse — ^to  the  original  pulp  chamber. 
Caush^  has  well  investigated  this  subject.  He  writes: — ^" These 
semilunar  excavations  vary  much  in  size  as  well  as  in  number, 


Fig.  80. — Internal  absorption  of  dentine,  with  deposition  of  cementum-like 
material  in  the  pulp  cavity.  Magnified  45  times.  (From  a  section  in  the  col- 
lection of  Douglas  Caush.) 

varying  from  a  single  light  dip  or  depression,  as  found  in  the  earlier 
stage,  to  the  numerous  excavations  producing  the  complex  and 
irregular  outline  as  seen  in  the  advanced  stage." 

Very  often  this  removal  of  tissue  is  followed  by  deposition  of 
dense  osseous  material,  a  sharp  line  of  distinction  between  the  new 
and  the  old  marking  off  this  new  development  (Fig.  80).  The 
adventitious  structure  is  devoid  of  tubules — thus  differing  from  many 
forms  of  adventitious  dentine — ^and  is,  therefore,  not  dentine;  but 
it  is  composed  of  lacunse  and  canaliculi  imbedded  in  a  granular 

'Trans.  World's  Columbian  Dental  Congress,  p.  114,  et  seq.,  1894. 
S 


66  THE    DEXTAL    TISSUES 

matrix,  as  in  hyperplasic  cementum.  The  lacuna  vary  in  number, 
size  and  position:  thus  they  may  be  placed  very  closely  together, 
or  scattered  throughout  the  mass.  In  the  former  they  possess 
short,  in  the  latter  elongated  canaliculi. 

In  explanation  of  the  modus  operandi  by  which  these  changes 
are  wrought,  Caush  describes  alterations  in  the  shape  of  the  odon- 
toblasts, which,  under  the  influence  of  hyperaemic  or  inflammatory 
conditions  of  the  pulp  undergo  sub-division  by  mitosis.  The  cells 
in  contact  with  the  dentine  begin  to  absorb  that  tissue,  their  func- 
tion being  more  rapidly  carried  on,  and  far  more  reaching  in  its 
effects,  if  the  dentine  forming  the  boundary  of  the  root  canal  hap- 
pens to  be  somewhat  poorly  calcified  or  developmentally  defec- 
tive. Caush  inclines  to  the  belief  that  the  odontoblasts  can  be- 
come converted  into  osteoclasts,  which,  later  on  (that  is  to  say,  when 
their  absorptive  energies  are  concluded),  become  again  changed  to 
formative  cells  and  manufacture  the  osteoid  cementum-like  tissue. 
He,  however,  gives  no  drawing  of  giant  cells.  They  are  not  re- 
quired: the  mere  effect  of  the  inflammatory  products  themselves, 
viz.,  the  phagocytic  leucocyte,  being  sufficient,  per  se,  to  produce 
the  excavation. 

In  this  connection,  an  instructive  case,  described  by  F.  J.  Bennett 
in  The  Dental  Record  for  June,  1899,  may  be  quoted,  summing  up, 
as  it  does,  very  succinctly  the  salient  pathological  features  of  inter- 
nal absorption.     He  writes: — 

''Whilst  examining  a  collection  of  old  teeth,  the  following  speci- 
men came  under  my  notice,  which  is  of  interest,  partly  from  its 
presenting  a  pathological  condition  of  uncommon  degree,  and 
also  as  illustrating  the  steps  employed  by  nature  for  the  removal 
and  repair  of  injured  tissues. 

"The  tooth  was  a  well- formed  lower  molar  which  had  been  at- 
tacked by  caries  upon  the  proximal  surface  at  its  junction  with  the 

cervical  region On  section,  the  pulp  canals  were  found  to 

be  empty,  and  showed  no  signs  of  having  been  treated.  The  surface 
of  the  roots  presented  the  usual  appearance  of  long  continued 
chronic  inflammation,  being  thickened  with  patches  of  porous  light- 
coloured  cementum,  and  having  vascular  canals  here  and  there 
penetrating  the  substance  of  the  tooth.  Indeed,  it  was  due  to  one  of 
these  apertures  of  unusual  size,  and  with  rust  coloured  margins,  that 
attention  was  first  called  to  the  case.  Situated  midway  between  the 
neck  and  the  apex  of  the  anterior  root,  it  was  found  on  section  to 
terminate  in  two  large  cavities  representing  the  pulp  canal,  which  at 


PATHOLOGICAL    CONDITIONS    Of    THE    DENTINE  67 

this  point  had  become  extended  in  various  directions  greatly  beyond 
its  original  size. 

"Under  the  microscope,  it  was  found  that  the  cavities  and  the 
channels  leading  to  them  were  everywhere  attacked  by  absorption, 
presenting  the  conspicuous  lunated  outlines  known  as  Howship's 
foveolae  or  lacunae.  The  margins  were  also  stained  with  the  rust 
colour  of  hasmatin  crystals. 

"The  cementum  covering  the  root  was  thickened,  and  towards 
the  apex  there  were  signs  of  alternations  of  absorption  and 
deposition. 

"This  direct  and  extensive  attack  upon  the  interior  of  the  tooth 
suggests  the  existence  of  some  source  of  irritation  within  the  root 
injurious  to  the  surrounding  cementum  and  periosteum;  and  fur- 
ther, that  it  was  for  the  removal  of  this  source  of  mischief  that  the 
process  of  absorption  was  set  in  action. 

"Quite  recent  investigations  have  shown  that  leucocytes  are  the 
essential  agents  in  the  process  of  absorption,  the  mass  of  highly 
vascular  granulation  tissue  found  Hning  these  absorption  cavities 
being  the  means  by  which  the  absorption  cells  are  brought  into  actual 
contact  with  the  affected  tissue.  These  absorption  leucocytes  or 
phagocytes,  migrating  from  the  capillary  vessels  of  the  granulation 
tissue  singly,  or  uniting  together  to  form  giant  cells,  attack  and 
take  into  their  interior  the  particles  to  be  removed. 

"The  recognition  of  the  nature  of  the  osteoclasts  as  originating 
in  the  leucocytes  may  be  considered  as  a  great  step  in  advance, 
as  it  leads  one  to  regard  many  of  the  processes  at  work  in  the  hard 
and  soft  tissues  as  essentially  similar  in  nature.  According  to 
Ziegler,  'Recent  researches  into  the  absorption  of  bone  appear  to 
place  it  on  a  level  with  absorption  of  other  tissues,  and  to  view  them 
all  from  the  same  standpoint. '"• 

"Although  it  is  common  in  the  soft  parts  and  in  bone  to  find 
diseased  tissue  becoming  detached  in  the  form  of  a  slough,  or  of  a 
sequestrum  at  its  hne  of  junction  with  the  healthy  tissue,  by  the 
interposition  and  activity  of  the  phagocytes,  this  is  possible  only  in 
tissues  possessing  a  vascularity  sufficient  for  the  conveyance  of  the 
cells  to  this  situation.  The  cementum,  however,  possesses  no  such 
system  of  capillary  vessels  throughout  its  substance  for  the  circula- 
tion of  blood  cells,  as  in  the  case  of  the  Haversian  canals  of  bone; 
consequently  this  method  of  removal  of  diseased  tissue  by  exfolia- 
tion does  not  occur.  The  process  adopted  in  this  instance  is  essen- 
'  Ziegler's  "General  Pathology  and  Anatomy,"  p.  160. 


68  -  THE    DENTAL    TISSUES 

tially  similar  to  that  occurring  in  the  molecular  absorption,  or  true 
caries,  of  bone.  The  phagocytes  channel  a  passage  ....  the 
channel  becomes  lined  with  the  granulation  tissue  which  penetrates 
the  dentine  and  ultimately  spreads  itself  over  the  surface  of  the  root 
canal,  allows  the  migrating  cells  to  absorb  and  remove  the  diseased 
dentine  down  to  the  surface  of  the  living  cementum. 

"  I  am  inclined  to  regard  this  specimen  as  illustrating  a  conserva- 
tive aim  on  the  part  of  Nature.  The  form  of  the  absorption  is  dif- 
ferent from  that  usually  seen  in  permanent  teeth  which  are  being 
shed.  In  the  latter  case,  the  root  is  either  shortened  or  reduced  in 
circumference,  and  the  cementum  is  equally — if  not  more — absorbed 
than  the  dentine.  In  this  specimen  the  struggle  to  maintain  the 
cementum  in  an  efi&cient  condition  is  exemplified  by  the  patches  of 
removal  and  redeposition  of  cementum  which  occur  in  various 
places. 

"  I  have  not  met  with  an  instance  in  which  repair  has  followed  to 
such  an  extent  that  the  root  cavity  comes  to  be  again  occupied 
by  fresh  nutrient  tissue,  but  a  remarkable  specimen  described  and 
figured  by  Salter^  inclines  me  to  the  belief  that  this  may  sometimes 
take  place.  In  this  case  well-formed  bone  with  Haversian  systems 
had  come  to  occupy  a  large  portion  of  the  pulp  cavity,  which  latter 
bore  traces  of  previous  lacunar  absorption.  The  pulp  cavity  had 
three  circular  apertures  entering  it  from  the  external  surface  a 
little  below  the  neck,  and  these  were  also  lined  by  bony  tissue.  The 
ossification  of  granulation  tissue  in  my  own  specimen  would  probably 
have  led  to  similar  appearances." 

True  bone,  identical  with  the  compact  variety,  may  fill,  under 
rare  conditions,  all  the  interspaces  of  internal  absorption  of  dentine. 
In  such  cases,  the  Haversian  systems  are  large,  the  lacunse  numerous, 
and  the  osseous  lamellae  pronounced,  while  large  irregular  spaces 
probably  contain  in  the  recent  state  portions  of  the  included  pulp. 
Four  well-authenticated  specimens  are  on  record,  one  described  by 
Messrs.  John  Ackery  and  J.  F.  Colyer  {Trans.  Odonto.  Soc.  of 
Great  Britain,  p.  66,  1893),  a  second  by  Salter,  a  third  by  Tomes 
(Trans.  Odonto.  Soc.  p.  178,  1899),  ^^^  ^^^  ^^^^  ^°w  published  with 
a  photomicrograph  for  the  first  time. 

The  first  case  was  as  follows: — 

A  partially-erupted  premolar  in  the  mouth  of  a  patient  of  ^7, 
years  of  age,  exhibiting  caries,  was  removed  on  account  of  irregu- 

1  "Dental  Surgery  and  Pathology,"  p.  79. 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  69 

larity  in  position.  The  root  was  only  two-thirds  completed.  It  was 
difficult  to  say  whether  this  diminution  in  size  was  due  to  arrested 
development  or  absorption;  but  the  latter  was  the  more  plausible 
theor}^ 

"The  transverse  sections  showed  that  the  dentine  contained 
in  its  midst  true  bone.  In  one,  taken  near  the  crown,  two  or  three 
small  canals  were  seen  containing  tissue  exactly  like  bone.  In  a 
lower  section,  a  large  portion  of  the  dentine  had  been  replaced  by  a 
tissue  very  irregular  in  character,  but  being,  in  places,  of  a  distinctly 
osseous  character.  To  the  side  of  this,  but  yet  separated  from  it, 
was  another  oval  space  containing  distinct  osseous  tissue.  In  a 
third  section  these  two  spaces  had  fused  together,  and  the  first  had 
progressed  much  further  into  the  dentine.  The  tissue  towards  the 
pulp  chamber  still  retained  the  irregular  character  already  spoken  of, 
but  in  the  portion  most  distant  from  the  pulp  there  was  distinct 
osseous  tissue  with  well-marked  Haversian  systems.  The  next 
section  showed  a  still  greater  portion  of  the  dentine  replaced  by 
true  bone,  the  irregular  tissues  only  being  apparent  in  that  part 
nearest  to  the  pulp  chamber." 

Salter's  specimen^  was  a  molar  having  three  canals  piercing 
the  cervical  region  just  below  the  edge  of  enamel.  Vertical  sec- 
tions were  made,  and  revealed  the  following: — The  substance  around 
the  canals  was  yellower  and  more  translucent  than  the  normal  den- 
tine, extended  for  some  distance  into  the  crown,  and  down  the  side 
of  one  of  the  roots.  Examination  with  the  microscope  proved  this 
to  be  cancellous  bone  in  all  its  salient  features — small,  uniformly 
sized  and  regularly  arranged  lacunae,  with  few  small  canaHcuH,  and 
even  and  regular  lamellae  placed  parallel  with  the  outhnes  of  the  can- 
celli.  The  line  of  demarcation  between  bone  and  dentine  was 
strikingly  sharp,  though  here  and  there  isolated  patches  of  the 
latter  were  inextricably  mixed  up  with  the  former. 

For  the  last  example,  the  author  is  indebted  to  the  courtesy  of 
Mr.  H.  R.  Pring.  A  maxillary  first  incisor  from  an  old  patient 
became  loose,  and  on  removal  was  seen  to  have  an  absorbed  root. 
Median  coronal  sections,  viewed  microscopically  from  within, 
gave  the  appearances  of  a  spicule  of  bone  in  dentine.  Histolog- 
ically, the  tissue  was  true  compact  bone,  as  is  seen  in  the  photo- 
micrograph (Fig.  81).     It  requires  no  special  description. 

^  Op.  cit.  p.  97. 


70 


THE   DENTAL   TISSUES 


Fig.  8i. — Vertical  section  of  human  incisor  with  internal  absorption  of  dentine, 
and  deposition  of  true  compact  bone.  Prepared  by  grinding.  Stained  with 
impregnation  by  coloured  collodion.  Magnified  50  times.  D.  Primary  dentine; 
A.  Area  of  absorption;  B.  Compact  bone;  Si.  Large  Haversian  canal;  S2. 
Small  Haversian  canal;  c.  Hyperplasic  cementum. 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE 


71 


(viii)  Adventitious  Dentines 

Definition. — Tissue  of  a  pathological  nature  which  has  been 
added,  in  the  course  of  dental  caries,  and  in  erosion,  to  the  primary 
or  first-formed  dentine. 

Etiology. — Inflammatory  conditions  of  the  pulp,  the  result  of 
penetrating  or  deep  caries  of  the  dentine  produces  stimulation  of 


'    ^  u  *  ^l#-  ^ 


^t. 


M,  U;: 


.^rw 


I        v,Vn     ■  \  V 


Fig.   82. — Areolar    adventitious    dentine.      Magnified    500    times,     d.   Primary 
dentine;  a.  Areolar  spaces  filled  with  detritus;  f.   Connective-tissue  fibres. 

the  peripheral  cells — not  odontoblasts — of  the  pulp,  which  then 
proceed  to  lay  down  a  new  form  of  dentine. 

Macroscopical  Appearances. — None. 

Secondary  Changes. — Certain  varieties  may,  under  the  influence 
of  advancing  caries,  become  infected  with  micro-organisms.  Of  all 
the  varieties,  except  the  hyaline,  to  be  presently  noted,  each  is 
liable  to  this  infection. 

HISTOLOGY 

Microscopically  considered,  there  are  five  varieties: — {a)  areolar, 
(jSj  cellular,  (7)  fibrillar,  (5)  hyaline,  and  (e)  laminar. 


72 


THE   DENTAL    TISSUES 


(a)  Areolar 

Its  general  characteristics  resemble  those  of  dentine  filled  with 
interglobular  spaces  (Fig.  82).  It  intervenes,  as  a  tissue  of 
repair,  between  a  carious  cavity  and  the  pulp.  Modified  tubules 
may  or  may  not  accompany  it.  When  they  do,  they  are  sparingly 
filled  with  round  and  rod-shaped  micro-organisms,  enlarge  greatly 
as  they  extend  inwards,  and  terminate  with  wide  open  mouths  at 
their  pulpar  extremities.  Probably  this  widening  of  the  tubes  is 
due  to  partial  softening  of  the  intertubular  matrix. 


Fig.   83. — Areolar    adventitious    dentine.      Magnified    250    times, 
dentine;  a.  Areolar  dentine;  p.   Pulp  tissue. 


D.   Primary 


It  forms  a  thick  sheet  of  hard  material,  devoid  of  ordinary  dentinal 
tubules,  being  constructed  of  partially-fused  calcospherites  in  the 
ordinary  way.  Its  free  edge  is  covered  with  round  cells.  Hyperae- 
mia  of  the  pulp  accompanies  its  formation.  It  is  the  most  com- 
monly recurring  of  all  kinds,  and  may  be  associated  with  the  fibril- 
lar variety,  as  in  the  foregoing  illustration. 


(j3)  Cellular 

This  is  probably  the  same  as  that  just  described,  with  the  addition 
of  the  presence  in  the  matrix,  of  cells  which  may  be  fusiform  or  round. 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE 


73 


The  former  are  common  when  an  areolar  condition  is  present,  the 
latter  when  a  hyahne  matrix  invests  certain  round  or  spindle  cells 
of  the  pulp.  They  are  caught  unawares,  so  to  speak,  in  the  osseous 
flood  poured  out  round  and  about  them. 

The  cells  vary  very  much  in  size,  the  innermost  being  six  or  eight 
times  as  large  as  the  smaller  ones  near  the  dentine.  Towards  the 
former  side,  rows  of  encapsuled  cells  may  exist,  some  being  multi- 
nucleated as  if  they  had  undergone  mitosis.  The  surrounding  pulp 
tissue,  in  immediate  relationship  with  the  new  deposit,  consists 
mainly  of  fusiform  cells  arranged  in  bundles  interspersed  with  small 


Fig.   84. — Cellular    adventitious  dentine.      Magnified  250  times,     n.   Nuclei  of 
encapsuled  cells;  M.   Matrix. 


round   cells,   the  former  possessing  oval  and   the  latter  rounded 
nuclei. 

(7)  Fibrillar 

Fibrillar  adventitious  dentine  bears  a  close  resemblance  to  ordinary 
dentine;  but  the  tube-like  structures  are  much  finer  and  less  regular 
than  in  ortho-dentine.  It  is  extremely  probable,  though  not 
admitting  of  easy  demonstration,  that  the  lines  are  actually  con- 
nective tissue  fibres,  and  not  hollow  tubes. 

The  dentine  is  deposited  in  layers,  and  presents  a  characteristic 


74 


THE    DENTAL    TISSUES 


fibrillar  structure.  It  is  observed  in  cases  of  chronic  caries.  On 
the  border  line  of  the  hard  and  soft  parts,  the  connective  tissue 
formation  of  the  dentine  is  strikino-lv  established. 


(5)  Hyaline 

This  kind  of  new  dentine  has,  as  its  favourite  site,  the  base  of  a 
carious  excavation  into  the  pulp  cavity.  It  may  be  irregularly 
rounded  in  shape.  Its  structure,  in  some  places,  conforms  to  that 
of  a  more  or  less  homogeneous  ground-glass-like  matrix  similar  to 


Fig.   85. — Fibrillar    adventitious    dentine.      Magnified    250  times,     d.   Primary 
dentine;  F.  Fibrillar  dentine. 

that  of  hyaline  cartilage;  in  others,  it  has  a  distinctly  granular  or 
fibrous  appearance. 

Distributed  at  its  margins,  cellular  adventitious  dentine  may  be 
often  observed. 

It  is  associated  with  chronic  inflammation  of  the  pulp,  especially 
when  this  has  fungated  through  the  opened  pulp  chamber,  granu- 
lated and  produced  a  soft  tumour  in  the  carious  cavity  of  the  crown 
of  the  tooth — productive  inflammation  of  the  pulp,  formerly  called 
"polypus." 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  75 


Fig.  86. 


-Hyaline    adventitious    dentine.      Magnified    250  times.      H.   Hyaline 
dentine;  p.   Pulp  tissue. 


Fig.   87. — Laminar     dentine.      Magnified     250     times.       D.     Primary     dentine; 
L.  Laminar  dentine;  p.   Pulp  tissue. 


76  THE   DENTAL   TISSUES 

(e)  Laminar 

The  variety  thus  described  also  may  be  associated  with  it  in 
laminated  form,  in  which  patterns  simulating  pulp  nodules  appear. 
In  fact,  it  is  possible  that  these  bodies  are  metamorphosed  pulp 
nodules. 

(ix)  Pathological  Pigmentation 

Pigmentation  of  the  dentine  may  be  partial  or  complete,  pink 
or  green  of  varying  shades  or  degrees.  It  never  exists  alone,  the 
cementum  and  very  rarely  the  enamel  sharing  its  staining. 

Definition. — A  permanent  coloured  condition  of  the  dentine. 

Etiology. — Never  a  congenital  defect,  it  differs  from  like  conditions 
of  enamel,  in  the  fact  that  it  may  be  produced  in  one  of  two  ways, 
each  of  which  leads  to  different  results.  Thus:  If,  as  a  consequence 
of  a  blow  on,  or  damage  to,  the  pulp  through  mechanical  or  chemical 
agencies,  an  artery  is  ruptured,  there  may  be,  under  favourable 
circumstances,  an  escape  of  oxyhaemoglobin  into  the  neighbouring 
structures.  The  colouring  matter  of  the  blood  permeates"  the 
dentinal  tubules,  and  sets  up  both  superficial  and  deep  areas  of 
haematogenous  pigmentation.     Here  the  colour  is  pink. 

In  the  second  case,  staining  of  a  green  character  is  due  to  the 
discoloration  of  the  tissues,  either  through  death  of  the  organic 
parts,  or  through  the  introduction  into  the  root  canals  of  some 
filling  material,  as  is  induced  by  some  kinds  of  amalgam,  especially 
those,  it  is  believed,  which  contain  salts  of  copper. 

Precisely  how  this  is  brought  about  is  unknown. 

Macroscopical  appearances  are  unnoticed  till  the  tooth  has  been 
removed  from  the  mouth.  The  cementum  is  stained,  and  on 
breaking  the  dentine  in  a  vice  it  also  is  found  coloured  through- 
out. 

(x)  Senile  Dentine 

While  enamel,  once  fully  formed,  is  incapable  of  undergoing  any 
further  changes  incidental  to  old  age,  dentine,  especially  in  the 
radicular  regions  of  teeth,  is  often  affected  by  them. 

Definition. — The  dentine  of  old  age. 

Etiology. ^-The  cause  may  be  attributed  to  a  weakened  or  dimin- 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE 


77 


ished  nutritive  supply,  producing  trophic  changes  primarily  in  the 
pulp  and  secondly  in  the  hard  tissues. 

Macroscopical  Appearances. — The  dentine  and  cementum  are 
rendered  yellow  or  brown,  and  the  apices  of  the  roots  become  semi- 
transparent,  or  in  long-continued  cases  quite  transparent. 

Secondary  Changes. — None. 

HISTOLOGY 

The  matrix  is  granular;  the  tubes  are  not  narrowed,  but  are 
apparently  absent.     This  is  not,  however,   the  case;  an  internal 


•\* 


Fig.   88. — Senile  dentine.      Magnified    45    times,     d.    Primary  dentine;  s.    Pri- 
mary dentine  which  has  undergone  senile  changes;  p.   Calcified  pulp. 

change  has  made  them  by  transmitted  light  assume  or  approximate 
to  the  same  refractive  index  as  the  matrix.  They  cannot  be  stained. 
Little  is  known  with  certainty  as  to  what  has  occurred,  but  it  is 
extremely  likely  that  they  have  become  occluded  throughout  their 
extent,  wholly  or  partially,  by  a  deposition  of  calcified  material 
within  their  walls.  They  are  no  doubt  solid,  and  incapable  of 
transmitting  sensations  to  the  pulp. 

The  tubules  and  their  contents  were  believed  to  undergo  fatty 
degenerative   changes  by  Heider  and   Wedl,   who,   in   their  well- 


78 


THE    DENTAL    TISSUES 


Fig.   89.— Vertical  section  from  a  senile  tooth.     Prepared  by  grinding.      Un-   , 
stained.      Magnified    35  times.     E.    Enamel;  d.    Primary  dentine;  C.    Calcified 
pulp.      {From  a  specimen  in  the  collection  of  G.  W.  Watson.) 


PATHOLOGICAL    CONDITIONS    OF    THE    DENTINE  79 

known  Atlas,  in  Fig.  75,  describe  a  varicose  condition  of  the  tubules. 
The  enlargements  contained  fatty  shining  granules,  arranged  in 
pater-noster-\ike  rows.     They  were  associated  with  free  fatty  drops. 

Accompanying  senile  dentine,  the  pulp  cavity  is  generally  filled, 
as  in  Figs.  88  and  89,  with  a  dense  deposit  of  secondary  dentine, 
and  there  is  nearly  always  present  a  certain  amount  of  cemental 
hyperplasia. 


CHAPTER   III 
THE  PATHOLOGICAL  CONDITIONS  OF  THE  CEMENTUM 

Microscopical   Elements   in: — (i)    Cemental  nodules;    (ii)  Ankylosis; 
(iii)  Hyperplasia;  (iv)  Senile  cementum. 

A. DEVELOPMENTAL   AFFECTIONS 

(i)  Cemental  Nodules 

Definition. — Sessile  circumscribed  tumours  of  the  cementum,  which, 
in  man,  are  extremely  rare.     They  may  be  called  ''cementomata." 

Etiology. — They  are  produced  by  local  development  and  calcifica- 
tion of  the  osteoblasts  of  the  periodontal  membrane. 

Macroscopical  appearances  are  the  same  as  in  enamel. 

Secondary  Changes. — None. 

HISTOLOGY  I 

The  dentine  is  normal  and  the  granular  layer  of  Tomes  presents 
no  changes. 

The  cemental  matrix  is  structureless,  and  extends  as  a  thin  layer 
over  the  dentine. 

The  neoplasm  is  made  up  of  arcuate  bands  of  matrix  with  laminae 
and  canaliculi.  Fairly  numerous,  the  first  formed  layers  are  dense 
and  more  lacunated  than  the  youngest  portion.  The  inflammation 
of  the  periodontal  membrane  has  undergone  resolution,  indicated 
by  the  formation  of  the  homogeneous  layer  of  cementum  most 
externally.  The  photomicrograph,  Fig.  90,  shows  a  nodule  which 
existed  at  a  locality  6  mm.  below  the  cervical  edge  of  a  mandibular 
molar.     The  specimen  is  believed  to  be  unique. 

B. — ACQUIRED   DISEASES 

(ii)  Ankylosis  or  Synostosis 

Definition. — Solid  osseous  union  between  roots  of  teeth  and 
their  containing  alveolar  sockets.     The  condition  must  not  be  con- 

80 


PATHOLOGICAL   CONDITIONS    OF   THE    CEMENTUM 


8l 


fused  with  "False"  gemination  of  teeth,  for,  in  the  latter,  the  pre- 
existing sockets  have  been  completely  destroyed  by  absorption 
processes. 


ON 


Fig.  90. — A     cemental     nodule.     Prepared     by     grinding.     Unstained.      Mag- 
nified 15  times.     D.   Dentine;  c.   Normal  cementum;  c.N.   Nodule.     Cf,  FiG.  10. 


Fig.  91.— Mesial  aspect  of  a  human  second  maxillary  molar  with  ankylosis  of 
its  root  to  the  jaw.     Slightly  enlarged.      {From  an  original  photograph.)     . , 

Etiology. — Inflammation  of  the  periodontal  membrane  aggravated 
or  accelerated,  or  even  perhaps  originally  produced  by  certain  con- 
stitutional dyscrasia,  such  as  gout,  rheumatism  or  other  trophic 
neuroses  produces  it.  The  probable  course  of  the  pathological 
phenomena  is  as  follows  :^ — The  root  membrane  having  been  attacked 
6 


82  THE    DENTAL    TISSUES 

by  septic  or  infective  micro-organisms,  during  the  course  of  the 
inflammation,  becomes  injected  with  blood  due  to  hyperaemia  and 
rapidly  becomes  infiltrated  with  inflammatory  products.  Sup- 
puration ensues.  The  whole  of  the  membrane  then  undergoes  con- 
version into  a  thick  mass  of  granulation  tissue.  The  adjacent  bone  of 
the  jaw  soon  gets  permeated  with  inflammatory  products,  and  under- 
goes a  kind  of  rarefying  osteitis,  or  ulceration.  Thus  a  small-cell 
exudation  invades  the  Haversian  canals  of  the  alveolus,  and  together 
with  osteoclasts  which  may  be  increased  in  number,  destroys  portions 
of  the  bone,  and  soon  is  changed  into  granulation  tissue,  which  joins 
with  the  granulation  tissue  of  the  root  membrane. 

On  the  cementum  side  these  pathological  phenomena  do  not 
make  such  marked  progress.  But  it  is  conceivable  that  the  small- 
cell  exudation  excavates  the  periphery  of  the  cementum,  producing 
a  roughening  of  the  exposed  surface,  and  that  the  granulation 
tissue  of  the  membrane  rapidly  passes  into  and  fills  the  irregular 
spaces  so  produced. 

The  layers  of  granulation  tissue  having  presently  united,  a  fibrous 
stage  is  in  time  reached,  and  then  follows  ossification  of  the  entire 
parts. 

Macroscopical  Appearances. — Roots  of  teeth  so  affected  present 
a  bony,  rough,  dull  growth  on  their  extremities;  they  may  be  bathed 
in  purulent  effusion  (Fig.  91). 

Six  cases  of  synostosis  of  teeth  in  man  have  been  placed  on  record: 
one  occurring  in  the  practice  of  W.  A.  Whatford,  a  second  by  Storer 
Bennett,  a  third  by  M.  Choquet,  a  fourth  by  G.  W.  Watson,  a  fifth 
and  a  sixth  by  the  author.  As  possessing  many  points  of  interest, 
the  latter  three  may  be  now  described. 

MR.    WATSON's    case 

The  size  of  the  mass  of  bone  attached  to  the  tooth  was  remarkable, 
and  some  idea  of  its  bulk  may  be  obtained  from  the  following  par- 
ticulars:— Its  greatest  diameter  extended  in  length  17  mm.;  the 
greatest  depth  from  apex  of  the  posterior  root  equalled  about  4  mm. 
The  inter-radicular  regions  measuring  from  the  distal  ending  of  the 
dentinal  tubes  was  about  5  mm.     See  Figs.  92  and  93. 

HISTOLOGY 

The  specimens  were  made  from  a  carious  mandibular  molar. 
The  pulp  canals  showed  no  signs  of  change. 


PATHOLOGICAL    CONDITIONS    OF    THE    CEMENTUM 


83 


The  cementum  at  the  neck  of  the  tooth  was  normal,  that  is  to  say, 
structureless,  no  lacunae  being  present.  The  lamellae  and  incremen- 
tal lines  were,  however,  highly  pronounced. 

The  root  membrane  was  normal  just  below  the  cervical  margin; 
at  some  considerable  distance  above  the  apex  of  the  anterior  root 
it  is  deflected  for  a  short  length  over  the  bony  alveolus. 

The  granular  layer  of  Tomes  is  strikingly  broad,  and  its  constit- 
uents clearly  defined. 


Fig.  92. — Ankylosis  of  the  roots  of  a  human  mandibular  molar.  Prepared 
by  grinding.  Unstained.  Magnified  12  times,  r.  Apices  of  the  roots;  o. 
Osseous  tissue;  A.  Abscess  cavity.  {From  a  specimen  in  the  collection  ofG.  W . 
Watson.) 


The  cementum  towards  the  apical  space  becomes  trebled  or 
quadrupled  in  width,  with  marked  penetrating  fibres,  but  the  inner- 
most zones  are  devoid  of  lacunae  and  canaliculi.  The  middle  and 
outer  zones  are  characterised  by  the  presence,  arranged  in  parallel 
stripes,  of  incremental  lines  with  dense  striae  of  lacunas  and  canal- 
iculi. This  part  of  the  tissue  consists  of  a  dozen  or  more  rows  of 
lacunae  displayed  side  by  side  in  due  order  and  regularity.  The  band 
of  tissue  sweeps  round  the  apical  space,  and  diminishes  in  thickness 
as  this  is  reached. 


84 


THE    DENTAL    TISSUES 


The  apex  of  the  pulp  canal  is  a  little  enlarged  to  give  off  a  devious 
ill-formed  passage  into  a  large,  almost  globular  cavity,  which  from 
certain  signs  of  absorption,  probably,  in  the  recent  state,  contained 
pus. 

Round  the  internal  surface  of  this  root  the  cementum  is  enor- 
mously broad,  is  exceedingly  granular,  and  possesses  in  its  central 


Fig.  93. — Similar  to  the  preceding.  Magnified  50  times,  d.  Dentine; 
H.c.  Hyperplasic  cementum,  occupying  what  had  previously  been  the  periodontal 
membrane;  O.  Osseous  tissue. 

axis  many  irregular  lacuna.  The  neighbouring  surface  of  the  pos- 
terior root  is  noted  for  its  thickened  cementum,  myriads  of  lacunae, 
the  canaliculi  of  which  run  towards  the  middle  line.  The  apex  and 
distal  portions  of  the  second  root  present  granular  cemental  matrix, 
marked  granular  layer,  and  abundant  lacunae. 


PATHOLOGICAL   CONDITIONS    OF   THE    CEMENTUM  85 


Fig.  94. — Vertical  section  of  radicular  portion  of  a  human  premolar  anky- 
losed  to  the  jaw.  Prepared  by  decalcification.  Stained  with  hsematoxylene. 
Magnified  10  times.     R.  Root  of  the  tooth;  a.  Bone  of  jaw. 


Fig.  95. — Vertical  section  of  a  human  tooth  ankylosed  to  the  jaw.  R.  Root; 
B.  Bone  of  jaw.  The  absolute  continuity  of  the  two  hard  tissues  is  strikingly 
shown.      (From  the  collection  of  the  late  Storer  Bennett.) 


86  THE    DENTAL    TISSUES 

The  most  external  tissue  is  bone  of  the  alveolus  structurally 
altered.  There  is  little  attempt  at  the  regular  formation  of  Haver- 
sian systems.  The  thickest  masses  contain  many  elongated  spaces 
filled  with  soft  material,  and  lacunae  of  every  conceivable  form  and 
size — many  of  which  are  abrachiate — abound,  some  massed  together 
and  coalesced,  others  quite  discrete.  The  matrix  is  rough  and 
granular.  No  well-marked  osseous  lamellae  are  visible.  The  thinner 
region  consists  of  matrix  and  lacunae. 

At  that  portion  of  the  mass  furthermost  from  the  roots  the  tissue 
begins  to  assume  the  characteristic  appearances  of  cancellous  bone. 
The  sections  are  remarkable  from  the  absence  of  the  festooned  con- 
tours of  the  foveolae  of  Howship.  Figs.  91  and  94  are  teeth  from  the 
mouth  of  a  man  aged  41,  who  was  suffering 
from  suppuration  of  the  socket  of  a  tooth 
which  had  been  recently  removed.  The 
second  right  maxillary  premolar  and  the  second 
and  third  molars  presented  complete  synostosis 
of  the  roots.  Fig.  91,  from  a  photograph  by 
the  author,  shows  the  general  macroscopical 
appearances  of  the  second  molar,  which  was 
otherwise  normal;  and  the  photomicrograph 
of   low   power   magnification  is  that  of  a  de-      ^'^-    96.     Maxillary 

first      premolar     anky- 

calcmed  section  of  the  second  premolar,     t  ig.  losed  to  alveolar  bone. 
96    is    noteworthy    on    account   of    the    large 
amount  and  size  of  the  bone  ankylosed  to  the  root  of  the  premolar. 
Fig.  95   is  a  photomicrograph  of  one  of  Storer  Bennett's  speci- 
mens. 

(iii)  Hyperplasia^ 

Definition. — A  pathological  overgrowth  of  cementum  due  to 
increase  in  number  (not  size)  of  its  structural  elements.  The  con- 
dition has  been  called  "  hypertrophy  "^  of  the  cementum.  This  is 
incorrect,  as  it  is  an  inflammatory  thickening  of  the  tissue.  Syno- 
nyms:— Exostosis,  cementosis.  Analogue: — Osteoplastic  periostitis. 

1  See  "A  Handbook  of  Pathological  Anatomy  and  Histology,"  by  Professors 
Delafield  and  Prudden,  p.  93,  1902. 

2  By  a  simple  "hypertrophy,"  modern  pathologists  understand  simple  in- 
crease in  size  of  the  elementary  structures  of  a  part,  leading  to  structural  changes 
the  result  of  increased  nutrition,  being  dependertt  on  excessive  functional  activity 
of  the  constituents  of  that  part.  Thus,  the  following  examples  may  be  cited: 
hypertrophied  bone;  enlarged  and  dilated  heart  ("compensatory  hypertrophy"), 
congenital  macroglossia,  enlarged  tonsils,  etc. 


PATHOLOGICAL    CONDITIONS    OF    THE    CEMENTUM 


87 


Etiology. — Functional  activity  of  the  cells  of  the  periodontal 
membrane  under  the  influence  of  the  inflammation  of  chronic 
periostitis  induces  hyperplasia.  The  membrane  becomes  hyperae- 
mic  and  swollen,  and  a  small-celled  infiltration  occurs.  On  the 
inflammatory  products  becoming  organised  into  fibrous  tissue, 
ossification  of  the  inner  surface  may  supervene;  but  the  v/hole 
thickness  of  the  membrane  does  not  calcify. 

Secondary  Changes. — None. 

Macroscopical  Appearances. — The  affection  may  be  so  slight  as 
to  give  rise  to  no  appreciable  amount  of  tumefaction.     Ordinarily, 


Fig.  97. — Hyperplasia  of  the  cementum.     Prepared  by  grinding.      Unstained. 
Magnified  51  times.      {Photomicrograph  by  Douglas  Gabell.) 


however,  smooth  rounded  nodules  may  be  seen  after  removal  of 
teeth,  or  there  may  be  a  rough,  cancellous,  bulbous  growth.  The 
whole  or  part  of  the  root  may  be  diseased;  a  band  or  mass  of  new 
tissue  may  not  only  produce  apparent  or  real  elongation  of  the  roots, 
but  actually,  in  some  circumstances,  join  them  or,  occasionally, 
even  teeth  themselves  together.  This  condition  is  known  as 
"false  gemination"  (see  previous  chapter).  In  these  extreme 
cases  the  intervening  alveolar  septa  have  been  absorbed  by  the 
small  cells  (leucocytes)  of  the  inflamed  periodontal  membrane. 


THE    DENTAL    TISSUES 


Fig.  98. — Hyperplasia  of  the  cementum.      Magnified  150  times.     O.   Oldest,  or 
the  earliest  deposited  layer;    Y.  Youngest  layer. 


Fig.  99. — Lacunse  and  canaliculi  in  hyperplasic  cementum.  Prepared^  by 
grinding.  Unstained.  Magnified  170  times.  {Photomicrograph  by  Douglas 
Gabell.) 


PATHOLOGICAL    CONDITIONS    OF    THE    CEMENTUM  89 

To   the   naked   eye    the   root   membrane   appears   considerably 
thickened  and  reddened. 
Secondary  Changes. — None. 

HISTOLOGY 

The  microscopical  structures  vary  in  different  degrees.  Hyper- 
plasia may  be  limited  to  the  apex  of  a  root,  a  minute  portion  near  the 
enamel,  or  midway  down  the  side  of  the  root. 

The  chief  features  of  the  new  growth,  in  addition  to  the  amor- 
phous or  granular  matrix,  lamellae,  and  perforating  and  penetrating 
fibres,  are  lacunae  and  canaliculi.  It  has  generally  been  understood 
these  latter  bodies  exist  in  normal  cementum;  but,  as  has  already 
been  pointed  out  in  Chapter  V.,  Vol.  I.,  this  is  most  probably  an 
erroneous  idea.  It  is  appropriate  and  opportune,  therefore,  to 
describe  cemental  lacunee  in  this  place. 

The  lacunae  somewhat  resemble  those  of  bone  (q.v.) :  but  in  their 
form,  number,  size,  arrangement  and  extraordinary  length  and 
number  of  their  processes,  they  present  several  points  of  difference. 

A  cemental  lacuna  is  an  irregular  space.  In  dried  sections  it  is 
filled  with  debris  or  air,  in  the  fresh  state,  with  some  amount  of 
living  material.  It  may  be  rounded,  ovate,  plumiliform,  arbores- 
cent or  rimous  in  shape.  The  first  two  conditions  most  generally 
obtain.     The  lacunae  of  bone  are  much  more  regular. 

In  number,  these  bodies  vary  in  different  parts.  Thus  at  the 
cervical  margin  they  are  generally  absent.  Few  in  number,  and 
isolated  in  position,  they  are  found  midway  between  the  crown  and 
the  root;  while  in  the  apical  region  they  are  most  abundant.  In  man, 
the  thinnest  cementum  is  almost  devoid  of  them;  the  thickest  is 
always  accompanied  by  them. 

Lacunas  differ  in  size.  According  to  KoUiker,  they  may  range  in 
diameter  from  lo/x  to  40^  or  60/x.  These  are  average  measurements. 
They  are  larger  than  those  of  bone.  Those  having  the  greatest 
size  are  to  be  found  in  the  inter-radicular  regions  of  molar  teeth,  and 
also  wherever  the  cementum  is  thickest  (see  Figs.  102  and  109). 
There  is  no  definite  arrangement  of  their  position  as  in  compact 
bone;  they  are  placed  in  a  haphazard  fashion  throughout  the  matrix, 
though  sometimes  they  lie  in  series,  apparently  being  governed  in 
their  distribution  by  the  lamellae.  Their  processes  are  numerous 
ramified  channels,  commonly  known  as  canaliculi,  which  stretch  out 
for  some  considerable  distance  (sometimes  as  far  as  6/x  or  8//)  from 


90  THE    DENTAL    TISSUES 

the  lacuna,  to  which  they  very  often  give  a  jagged  plumihform  ap- 
pearance (see  Fig.  loi).  Branched  and  irregular  in  outline,  as  a 
rule,  these  offshoots  taper  towards  their  free  ends  where  they  com- 
monly measure  i^u.  Some  end  in  a  cul-de-sac;  others  anastomose 
with  neighbours;  others  again  form  the  minute  extremities  of  the 


Fig.  100. — Hyperplasia  of  the  cementum.  Prepared  by  grinding.  Stained 
by  impregnation  with  coloured  collodion.  Magnified  200  times.  Shows  the 
diversified  character  of  the  lacunas. 

dentinal  tubes  or  their  branches,  while  another  set  may  meet  with 
certain  processes  from  the  spaces  of  the  granular  layer  of  Tomes. 
In  slight  cases  of  hyperplasia  it  seems  to  be  a  normal  condition  for 
the  canaliculi  to  be  given  off  from  all  sides  of  the  lacuna;  still  there 
is  often  a  general  disposition  on  their  part  to  most  chiefly  extend 


PATHOLOGICAL   CONDITIONS    OF   THE    CEMENTUM  9 1 


Fig.   ioi. — Plumiliform  lacunae  in  hyperplasic  cementum.     Prepared  as  in  the 
preceding  figure.      Magnified  250  times. 


Fig.    102. — Rimous  and  arborescent  lacunae  in  hyperplasic  cementum. 
Prepared  as  in  the  preceding  figure.      Magnified  250  times. 


92 


THE    DENTAL    TISSUES 


outwards  towards  the  periodontal  membrane.  In  rimous  lacunae 
they  issue  at  right  angles  to  the  sides  as  well  as  the  ends;  and,  in  ad- 
dition, in  the  innermost  zone — viz.,  that  tirst  laid  down  by  osteo- 
blasts, the  outlines  of  the  lacunae  when  present  are  very  irregular, 
their  canaliculi  are  short  and  may  blend  intim.ately  with  many 
elongated    canals.     In    multi-rooted    teeth,    where    cementum    is 


••''i^« 


%^-    ■-%> 


^^'■^ 


4.^ 


Fig.  103.- 


-Cemental  lacunas  and  canaliculi.     Magnified  1,000  times. 
{Photomicrograph  by  Norman  Broomell.) 


slightly  thicker  than  elsewhere,  the  ground  substance  is  particu- 
larly granular;  if  lacunae  are  present,  they  are  fairly  evenly  distrib- 
uted throughout,  and  many  rimous  or  aborescent  spaces  are 
found  (see  Fig.  109). 

According  to  Tomes  {op.  cit.  p.  117),  some  lacunae  have  short  cana- 
liculi, and  are  encapsuled.  "  Sometimes  a  line  is  seen  to  be  surround- 
ing a  single  lacuna,  sometimes  several  are  enclosed  within  it." 
Capsules  are  not  very  common;  but,  if  present,  they  appear  clearly 


PATHOLOGICAL    CONDITIONS    OF    THE    CEMENTUM 


93 


defined,  are  yellowish  in  colour,  have  slightly  curved  borders,  and 
may  surround  an  individual  or  group  of  lacunae  either  partially  or 
entirely. 

What  constitutes  the  actual  contents  of  these  spaces  in  the  fresh 
state  has  been  up  to  the  present  time  only  imperfectly  known.  Most 
probably,  arguing  from  the  sensitiveness  of  this  tissue  when  exposed, 
each  is  filled  with  protoplasm.  Heitzmann  and  Bodecker  both  claim 
to  have  proved  this  as  a  physiological  and  histological  fact. 

And  it  is  a  common  experience  to  find,  in  sections  of  hyperplasic 
cementum,  when  properly  prepared,  lacunae  containing  a  nucleated 


Fig.    104. — Cemental  lacunee  in  the  first-deposited  layers  of  cementum. 
fied  80  times.      {Photomicrograph  by  Norman  Broomell.) 


Magni- 


cell,  analogous  most  probably  to  the  bone  corpuscles  of  ordinary 
osseous  tissue. 

In  addition,  the  incremental  lines  of  Salter,  generally  speaking, 
are  strikingly  exhibited  in  ground  as  well  as  in  decalcified  sections. 
They  are  not,  however,  always  constant,  as  in  Fig.  105. 

If  the  deposition  of  the  tissue  has  been  conducted  on  uniform  lines, 
the  laminae  are  very  regular,  the  lacunae,  though  numerous,  bear  also 
some  definite  relationship  to  each  other,  and  are  systematically 
arranged  with  regard  to  the  laminae  (see  Fig.  107).     But  when  the 


94 


THE    DENTAL    TISSUES 


Fig.   105. — Hyperplasia  of  the  cementum.      Prepared  by  grinding.      Unstained 
There  are  no  incremental  lines.      Magnified  40  times. 


HC 


Fig.  106. — Hyperplasia  of  the  cementum.  Transverse  section  through  apical 
region  of  tooth.  Magnified  40  times,  d.  Dentine;  R.c.  Root  canal  somewhat 
enlarged  and  containing  a  deposit  of  ossific  or  calcific  material;  H.C.  Hyperplasia 
cementum.      {Frorn  a  specimen  in  the  collection  of  Douglas  Caush.) 


PATHOLOGICAL   CONDITIONS    OF   THE    CEMENTUM 


95 


HC 


VC 


Fig.  107. — Hyperplasia  of  the  cementum.  Magnified  40  times.  D.  Dentine; 
H.C.  Cementum  in  which  the  lamina  are  regularly  arranged;  v.c.  Vascular  canal. 
{From  the  collecliott  of  Douglas  Caush.) 


HC 


Fig.  108. — External  absorption  of  dentine  and  deposition  of  hyperplasia 
cementum.  Magnified  45  times.  D.  Dentine;  a.  Area  of  absorption;  H.C. 
Cementum.      (From  the  colleclion  of  Douglas  Caush.) 


96 


THE   DENTAL   TISSUES 


Fig.   109. — Rimous  and  very  large  lacuna  in  hyperplasic  cementum.      Magnified 
45  times.      (From  the  collectioji  of  Douglas  Caush.) 


Fig.  1 10. — Internal  absorption  of  jifdentine,  enlargement  of  root  canal,  and 
deposition  of  osseous  or  calcific  material.  Magnified  40  times.  D.  Dentine; 
R.C.  Root  canal;  o.  New  tissue  deposited  in  the  root  canal;  h.C.  Hyperplasic 
cementum.      (From  the  collection  of  Douglas  Caush.) 


PATHOLOGICAL    CONDITIONS    OF    THE    CEMENTUM 


97 


Fig. 


III. — To  show  the  nature  of  the  new  tissue  deposited  in  a  root  canal 
Magnified  250  times.      {From  the  collection  of  Douglas  Caush.) 


Fig.  112. — External  absorption  of  dentine,  and  deposition  of  hyperplasia 
■cementum  in  the  absorption  areas.  Magnified  200  times.  (From  the  collection 
of  Douglas  Caush.) 


98 


THE    DENTAL    TISSUES 


Fig.   113. — Similar  to  the  preceding.      From  the  same  source.      Magnified  200 

times. 


Fig.  114. — Cementum  and  dentine  of  a  senile  tooth.  Prepared  by  grinding. 
Unstained.  Magnified  230  times,  c.  Granular,  but  not  lacunated  cementum; 
D.   Dentine. 


PATHOLOGICAL   CONDITIONS    OF   THE   CEMENTUAI 


99 


mass  is  lobulated  and  has  a  rugged  surface,  then  the  lacunae  are 
coarse,  large,  and  provided  with  long  branched  deviating  processes. 
In  the  former  degree  the  line  of  junction  with  the  dentine  is  sharp 
and  clear;  in  the  latter  it  is  often  impossible  to  say  exactly  where  one 
tissue  ends  and  the  other  begins. 


PM 


Fig.  115. — Senile  cementum  and  alveolar  bone.  Magnified  45  times.  D. 
Dentine;  C.  Hyperplasic  cementum;  p.m.  Periodontal  membrane;  B.  Osteo- 
porotic alveolar  bone. 

Newly  formed  vascular  channels  often  make  their  appearance 
in  the  cementum  (Fig.  107)  and  the  phenomena  of  absorption  and 
re-deposition  (Figs.  112  and  113)  take  place  side  by  side  in  the  same 
specimen.  The  condition  is  commonly  associated  with  enlargement 
of  the  pulp  canal,  and  sometimes  depositions  of  new  osseous  material 
(see  Figs.  io6  and  no). 


lOO  THE    DENTAL    TISSUES 

(iv)  Senile  Cementum 

Of  cementum  found  in  aged  teeth  little  need  be  said.  As  a  rule, 
it  is  hyperplasic,  because  few  teeth  which  have  been  removed  from 
the  mouth,  either  from  mobility  or  to  relieve  pain,  have  escaped  the 
ravages  of  disease,  and  their  cementum  is  therefore  thickened  and 


Pig.   ii6. 


-Senile  cementum.      Magnified  200  times,     d.   Dentine;  p.m.  Homo- 
geneous layer;  c.    Cementum. 


lacunated.  But  healthy  teeth,  which  have  never  been  the  subject 
of  an  attack,  show  that  this  tissue  is  somewhat  thicker  than  in 
young  adults,  but  is  structureless  and  similar  in  every  way  to  normal 
cementum  (see  Fig.  114.     Cf.  Fig.  97). 


CHAPTER  IV 
DENTAL  CARIES 

Microscopical  Elements  in: — (i)  Nasmyth's  membrane;  (ii)  "White 
spots;"  (iii)  Zones  of  partial  and  complete  decalcification;  (iv) 
"Secondary  enamel  decay;"  (v)  Zone  of  translucency;  (vi)  "Lique- 
faction foci;"  (vii)  "Pipe-stem"  appearance;  (viii)  Opaque  zones  of 
Miller;  (ix)  Cementum;  (x)  "Arrested"  caries. 

Definition. — "An  acid  fermentation  during  which  the  inorganic 
portions  of  teeth  are  first  dissolved,  and  then  the  organic  portions 
disintegrated  by  the  action  of  micro-organisms."  More  shortly: — 
Decalcification  of  the  teeth  followed  by  their  dissolution. 

Etiology.'^ — The  environment  of  the  teeth.  The  peptonising 
influences  of  micro-organisms  on  the  surface,  proceeding  inwards. 
Strictly  it  is  not  a  disease,  as  it  cannot  be  induced  at  will,  in  man 
or  the  lower  animals. 

Dental  caries  has  never  been  noted  in  the  teeth  found  in  ovarian 
teratomatous  cysts. 

Macroscopical  Appearances. — These  are  too  well  known  to  require 
any  special  description;  suffice  to  say  that  enamel  loses  its  polish; 
white,  opaque  "spots"  appear;  pigmentation  ensues;  and  in  the 
hard  parts,  cavities  are  produced.  According  to  certain  accompany- 
ing phenomena  it  has  been  termed  caries  acuta,  when  rapid  in 
progress;  caries  chronica,  when  slow;  caries  sicca,  when  dry;  and 
caries  humida,  when  saturated  with  fluids.  French  writers  speak 
of  caries  of  the  "ist  degree,"  "2nd  degree,"  and  so  on,  thus  hinting 
at  the  extent  which  has  taken  place. 

1  The  causes  of  Dental  caries,  it  may  be  stated  in  general  terms,  are  not  alto- 
gether known.  Some  authors  have  divided  the  causes  into  (A)  Predisposing,  {B) 
Exciting.  Of  these,  grouped  under  the  heading  of  General  predisposing  causes, 
one  finds,  (a)  Heredity,  ib)  Improper  dietary,  ic)  Civilization;  and  under  the 
heading  of  Local  predisposing  causes,  (a)  Malposition  in  the  dental  arches,  (6) 
Structural  defects  of  the  surface,  and  (c)  Vitiated  oral  secretions,  produced  by 
(i)  systemic  diseases,  e.g.,  gout,  typhoid  fever,  etc.;  (ii)  occupation,  as  in  millers, 
or  finally,  (iii)  pregnancy.  The  Exciting  cause  is:  Bacterial  fermentation  of 
carbo-hydrates.  It  is  difficult  to  name  the  true  cause  or  causes.  Probably 
a  hitherto  undiscovered  special  caries-producing  micro-organism  is  the  chief 
agent. 


I02 


THE   DENTAL   TISSUES 


Secondary  Changes. — The  condition  may  become  arrested;  but 
usually  it  extends,  unless  interrupted,  until  the  crowns  of  teeth  are 
destroyed  more  or  less  in  their  entirety. 

Phenomena. — The  probable  sequence  of  events  in  progressive 
caries  of  the  teeth  is  as  follows: — 

I. — Attack  on  Nasmyth's  membrane, 
2. — Formation  of  "white  spots"  in  enamel, 
3. — Channeling    and    penetration    of    enamel    by    micro- 
organisms. 


Pig.  117. — An  early  stage  of  caries  of  the  enamel.  Prepared  by  grinding. 
Unstained.  Magnified  45  times,  e.  Enamel;  d.  Dentine;  w.  "White  spot;" 
P.  Area  of  pigmentation;  f.s.   Free  approximal  surface  of  the  tooth. 

4. — Decalcification  of  dentine, 

5. — Tubular  infection  by  micro-organisms,  with  formation 

of  "liquefaction  foci," 
6. — Fusion  of  the  latter  and  production  of  cavities,  and 
7. — Dissolution  of  the  hard  parts. 
These  must  now  be  severally  described. 

HISTOLOGY 

(i)  Nasmyth's  memhrane 

Of  the  histo-pathology  of  this  tissue  little  is  known.  Its  extreme 
tenuity  and  its  anatomical  characteristics,   and  the  difl&culty  of 


DENTAL   CARIES 


103 


making  sufficiently  satisfactory  microscopical  preparations  have 
given  but  few  opportunities  for  pathologists  to  work  out  its  morbid 
anatomy. 

It  would  appear  that  the  tissue  is  often  more  or  less  deeply  pig- 
mented, probably  partly  through  the  agency  of  certain  chromogenic 
bacteria,  partly  through  the  use  of  tobacco,  or  the  salts  of  iron, 
copper  and  mercury,  and  partly  through  post  mortem  changes  common 
to  all  organic  matter;  and  finally  wholly  or  partially  removed  by  the 
action  of  micro-organisms  and  mechanical  agencies  from  the  surface 


NM 


WS 


Fig.  118. — Early  stage  of  caries  of  enamel.  Magnified  90  times,  n.m. 
Nasmyth's  membrane  increased  in  thickness  (?  rarious);  w.s.  "White  spot;" 
p.   Pigmentation  of  enamel;  e.   Non-carious  enamel. 


of  the  enamel.  It  is  believed  that  the  natural  acids  of  fermentation 
have  little  or  no  effect  upon  it,  since  the  translucent  pelhcle  is 
peculiarly  resistant  to  strong  acid  reagents  like  hydrochloric,  acetic, 
etc.  It  is,  however,  evident  that  the  enzymes  of  bacteria  are  able 
to  disintegrate  this  film  with,  probably,  the  production  of  a  small 
amount  of  amino-acetic  acid.  In  preparations  stained  by  Gram's 
method,  it  is  possible  to  see  masses  of  micrococci  congregated  on 
its  surface. 


I04 


THE   DENTAL   TISSUES 


*|ii::-lS^ 


Fig.   119. — A  portionof  a 


'  White  spot."      Magnified  2,000  times.      [Photoynicro- 
graph  by  Leon  Williams .) 


Fig. 


120. — Section  through  human  enamel,  showing  the  first  stages  of  caries. 
Magnified  2,000  times.      (Photomicrograph  by  Leon  Williams.) 


DENTAL    CARIES 


105 


Otto  Walkhoff  in  a  recent  work^  describes  and  figures,  in  Plate  XI., 
a  deposit  of  green  pigment  which  has  taken  place,  in  parallel  rows, 
between   the  '"convexities  of.  the  enamel."     This,  no  doubt,  refers 


Pig.  121 . — An  early  stage  of  caries  of  the  enamel  round  the  fissure  on  the  occlusal 
surface  of  a  human  premolar.  Prepared  by  grinding.  Unstained.  Magnified 
45  times,  p.  Carious  patch  at  free  end  of  a  deep  sulcus;  i.e.  Developmentally 
defective  enamel  rods;  r.  Brown  striae  of  Retzius;  a.  Amelo-dentinal  junction; 
D.   Dentine. 


to  the  thickest  portions  of  the  membrane  in  the  pits  and  crevices  of 
the  enamel. 

It  may,  however,  be  stated  that  the  precise  role  played  by  Nas- 
myth's  membrane  with  regard  to  dental  caries  is  not  at  present 

J  "Mikrophotographischer  Atlas  dcr  Pathologischer  Histologie  Menschlicher 
Zahne." 


io6 


THE    DENTAL    TISSUES 


understood.  It  would  seem,  however,  in  the  opinion  of  the  author 
to  constitute,  under  favourable  conditions,  the  first  line  of  defence 
against  dental  caries.  Pickerill,  and  Tomes  and  Nowell  ("A  System 
of  Dental  Surgery,"  1906)  present  the  hypothesis  that  it  may  act  as 


Fig.  122. — Similar  to  the  preceding,  but  caries  more  advanced.  Prepared 
similarly,  with  same  magnification.  Lettering  as  in  preceding  figure,  b.b. 
Breach  of  surface. 

a  dialysing  membrane  to  certain  substances,  which  may  disintegrate 
the  surface  of  the  enamel  and  lead  to  carious  changes  in  that  tissue. 


(ii)  "White  Spots" 

Quite  dark  by  transmitted  light,    and   often  surrounded   by  a 
pale   zone,  Fig.  117,  these  have   probably  the  same   histological 


DENTAL   CARIES 


107 


features  as  that  surrounding  the  pigmentation  areas  in  caries. 
The  enamel  rods  in  the  "white  spots"  are  exceedingly  granular, 
and  deeply  pigmented,  their  enamel  globules,  according  to  Leon 
Williams,  having  become  but  imperfectly  fused  owing  to  insuf- 
ficiency of  cement-substance  (Figs.  119  and  120).  Very  light  and 
deeply  pigmented  patches  of  enamel  alternate  irregularly  in  the 
immediate  vicinity  of  the  "white  spots." 


Pig.    123. — Caries     of     enamel.      Magnified     90     times,     m.    Micro-organisms; 
p.    Pigmentation  of  enamel;  d.   Decalcified  enamel;  c.   Decalcifying  enamel. 


(iii)  Channeling  by  Micro-organisms 

The  appearances  produced  by  the  earliest  action  of  the  acids 
generated  by  the  bacteria  upon  enamel  vary.  This  is  due  to  dif- 
ferences in  the  structure  of  the  tissue  as  well  as  to  the  variations  in 
the  products  or  peptonising  effects  of  the  micro-organisms  themselves. 
(Leon  Williams.)     (Figs.  127  and  128.) 

It  is  still  an  undecided  question  whether  the  "gelatinous  plaques"' 
of  Black^  and  Leon  Williams  do  really  exist.     They  are  beheved 
to  be  formed  by  masses  of  bacteria  which,  collecting  in  suitable 
1  Black,  G.  v.:  "Operative  Dentistry,"  Vol.  I,  1908. 


io8 


THE    DENTAL    TISSUES 


situations,  are  able  by  a  precipitation  of  mucilaginous  compounds 
to  focus  in  a  more  Or  less  widespread  but  yet  well-defined  fashion 
the  operations  of  the  destructive  agencies.  Kirk^  has  recently 
apparently  shown  that  it  is  possible  to  manufacture  "bacterial 
plaques"  to  any  size  or  extent  (Figs.  126  and  127).  The  author, 
however,  believes  that  these  "gelatinous  plaques"  are  in  reality 
nothing  more  nor  less  than  portions  of  Nasmyth's  membrane  which 
have  been  retained  in  situ.     For  the  free  surface  of  such  a  membrane 


Fig.  124. — Section  of  normal  human  enamel.  Magnified  350  times.  It  shows 
a  thick,  felt-like  mass  of  micro-organisms  slightly  raised  from  the  surface  of  the 
tissue  (Nasmyth's  membrane)  produced  by  pressure  of  the  cover-glass  in  mount- 
ing.     {Photomicrograph  by  Leon  Williams.) 

could  afford  attachment  for  material  which  might  become  a  suitable 
nidus  for  the  development  of  oral  bacteria. 

The  acid  dissolves  out  channels,  or  "wells,"  whose  walls  may  be 
parallel  or  V-shaped  (Fig.  126).  These  are  most  commonly  seen 
on  the  approximal  surface  of  teeth  of  man;  their  occurrence 
in  the  buccal  or  lingual  aspects  being  less  frequent.     They  penetrate 


^Kirk:  "A  Consideration  of  the  Question  of  Susceptibility  and  Immunity  to 
Dental  Caries,"  Dental  Cosmos,  1910. 


DENTAL    CARIES  lOQ 

the  intercolumnar  substance  between  the  rods,  not  the  rods  them- 
selves (Figs.  125  and  126).  They  are  often  larger  than  the  di- 
ameter of  a  rod,  and  are  in  no  sense  of  the  word  developmental 
defects,  but  merely  produced  by  the  acids  formed  by  the  enzymes  of 
the  micro-organisms  of  caries. 


Fig.  125. — A  section  of  human  enamel  showing  micro-organisms  attached  to 
the  approximal  surface  of  a  molar  tooth.  Magnified  200  times,  a.b.  The 
commencement  of  the  process  of  caries  by  solution  of  the  cement-substance. 
(Photomicrograph  by  Leon  Williams.) 

The  acid  passes  inwards  for  some  distance  by  means  of  these 
channels  without  the  production  of  discolouration. 

Dark  bands  in  enamel,  internal  to  the  line  of  acid  penetration, 
probably  represent  a  partial  arrest  in  the  action  of  the  micro- 
organisms, which  has  been  presumably  brought  about  by  some 
altered  conditions  of  the  environment  of  the  tooth  (Fig.  132). 

In   acute  caries  the  acid  penetrates   quickly  and  deeply  along 


no 


THE   DENTAL   TISSUES 


the  lines  of  least  resistance,  i.e.,  the  cement  substance,  the  rods 
themselves  undergoing  isolation,  and  becoming  disintegrated  before 
their  morphological  characters  are  lost.  In  chronic  cases,  however, 
the  whole  substance  of  the  rods  is  permeated  by  acid,  the  result  being 
the  appearance  of  a  "sponge-like  structure,"  giving  the  effect  of 


Fig.  126. — Section  of  human  enamel.  Magnified  350  times.  It  shows  a 
deeply  stained  mass  of  micro-organisms  attached  to  the  surface,  and,  at  w, 
further  action  of  the  acid  in  dissolving  the  cement-substance  and  forming  V- 
shaped  spaces  between  the  enamel  rods.      {Photomicrograph  by  Leon  Williams.) 

discolouration  in  sections  when  viewed  by  transmitted  light,  and 
chalky  white  by  reflected  light  (Leon  Williams). 

Thus,  acute  white  caries  is  unaccompanied  by  discolouration,  and 
is  due  to  solution  of  the  intercolumnar  substance;  chronic  caries 
to  impregnation  with  the  products  of  bacteria  and  associated  with 
marked  discoloration.  These  changes  are  macroscopically  invisible, 
and  occur  before  a  breach  of  surface  results. 


DENTAL    CARIES 


III 


With  regard  to  congenital  defects  in  enamel,  it  is  almost  con- 
clusively proved  that  they  are  not  favourite  sites  for  the  development 
of  caries;  but  that  the  micro-organisms  most  frequently  act  on  enamel 
which  is  not  over  the  cusps  of  teeth,  where  it  is  usually  most  defec- 
tive.    Caries  often  begins,  as  is  well  known,  from  a  clinical  stand- 


FiG.  127. — A  section  of  human  enamel  from  the  approximal  surface  of  an 
incisor.  Magnified  175  times.  Showing  enamel  nearly  penetrated  by  dental 
caries,  a.  The  carious  process  apparently  arrested  by  a  line  of  stratification. 
Micro-organisms  (attached  to  Nasmyth's  membrane)  slightly  raised  from  floor 
of  cavity  by  shrinkage  caused  by  mounting  in  balsam.  (Photomicrograph  by 
Leon  Williams.) 


point,  on  approximal  surfaces  of  the  teeth,  and  here  the  enamel  is, 
probably,  more  perfectly  formed  than  elsewhere.  But,  while  bac- 
teria act  independently,  there  is  no  doubt  that  they  avail  themselves 
of  the  presence  of  pits  and  fissures,  being  governed  in  their  disposi- 
tion on  the  surface  of  enamel  by  the  completeness  or  incompleteness 
of  the  translucent  pellicle  of  Nasmyth's  membrane.     The  explana- 


112  THE    DENTAL    TISSUES 

tion  would  appear  to  be,  that  having  once  penetrated  through  ar 
abraded  edge  of  the  membrane  they  can  pass  beneath  it  to 
some  considerable  distance.  If  this  is  true,  the  phenomena  of 
caries  beginning  in  pits  and  fissures  would  be  accounted  for. 

At  a  somewhat  later  stage,  carious  enamel,  under  the  microscope, 
shows  that  the  individual  rods  are  pronounced,  their  intercolumnar 


Fig.  128. — A  section  of  carious  enamel.  Magnified  550  times.  The  bacteria 
have  been  removed  to  shew  the  action  of  the  acid  on  the  enamel  rods.  {Photo- 
micrograph by  Leon  Williams.) 


substance  partially  loosened  (Figs.  128  and  130),  and  clearly  ex- 
hibiting spaces  between  the  enamel  columns.  The  striag  are  very 
marked.  This  is  on  the  surface.  Lower  down,  the  structure  is 
indistinguishable,  the  rods  are  confluent,  and  have  lost  their  outline; 
they  appear  exceedingly  granular.  Still  deeper,  they  have  dis- 
appeared, their  place  being  occupied  by  masses  of  micro-organisms, 
which  are  clearly  revealed  when  the  section  has  been  stained  with 


DENTAL    CARIES 


113 


Fig.  129. — A  section  of  carious  enamel,  showing  appearances  of  the  tissue  in 
a  case  of  chronic  caries.  Magnified  2,000  times.  The  cement-substance  has 
been  dissolved  away,  thus  exposing  to  view  the  original  organic  matrix.  The 
globular  bodies  or  sections  of  the  rods  are  shown  at  a,  b,  c,  d,  and  are  seen 
to  be  identical  in  general  shape  and  character  with  those  originally  formed  in 
the  ameloblasts  and  on  the  surface  of  forming  enamel.  {Ph  tomicrograph  by 
Leon  Williams.) 


114 


THE    DENTAL   TISSUES 


gentian-aniline-violet,  fuchsine,  or  other  aniline  dyes.  Bacteria 
may  be  seen  occupying  the  spaces  between  the  rods  if  a  minute 
fragment  of  "secondary  enamel  decay"  is  examined. 

The  loosening  of  the  rods  is  said  to  be  dependent  on  the  action 
of  lactic  acid.     Tomes  believes  that  the  axes  of  the  enamel  columns 


Fig.  130. — A  cover-glass  preparation  from  scrapings  of  white,  opaque  carious 
enamel.  Magnified  450  times.  The  cement  substance  between  the  rods  is  seen 
to  be  dissolved  away,  and  the  crevices  thus  formed  are  filled  with  round  and 
rod  forms  of  micrococci  and  bacteria.  Stained  by  Gram's  method.  {Photo- 
micrograph by  Leon  Williams.) 


are  attacked  before  their  peripheries.     This,  no  doubt,  is  the  case 
where  the  tissue  is  at  all  ill-formed. 

Hence    there  are   three   zones   or   areas   in   enamel  which  show 
different  appearances: — 

(i)  The  zone  of  partial  decalcification,  \\here  the  rods  are  in- 
dividually distinct,  the  striae  marked,  and  tie  cement  sub- 
stance partially  disintegrated, 


DENTAL    CARIES 


IIS 


(ii)  The  zone  of  complete  decalcification,  in  which  the  rods  are 
structureless,  but  possess  a  marked  degree  of  granularity; 
And 

(iii)  The  zone  of  "secondary  enamel  decay,"  in  which  masses  of 
micro-organisms  only  can  be  demonstrated  (see  Fig.  139). 


Fig.  131. — Caries  of  the  enamel,  having  produced  a  breath  of  surface.  Pre- 
pared by  grinding.  Unstained.  Magnified  45  times,  p.  Carious  patch  in 
enamel;  i.e.  Imperfect  enamel  rods;  R.  Striffi  of  Retzius;  D.   Dentine. 


(iv)  Decalcification  of  Dentine 

This  invariably,  in  a  fairly  regular  line,  precedes  the  bacterial 
infection  of  the  tubes.  The  dentine  stains  easily  with  histological 
reagents.  Unstained  it  is  pigmented,  being  pale  yellow  or  brown  in 
colour. 


ii6 


THE   DENTAL   TISSUES 


A  microscopical  appearance  of  great  importance  in  the  region  of 
advancing  decalcification  is  the  presence  of  the  "zone  of  translucency" 
(Fig.  137). 

The  term  is  applied  to  an  area  of  increased  transparency  in  that 
part  of  the  dentine  which  is  situated  between  the  advancing  caries 


Fig.  132. 


-A  further  stage  of  the  preceding  figure.      Prepared  similarly,  and  the 
same  lettering.      Magnified  25  times. 


and  the  healthy  tissue.  In  longitudinal  sections  it  often  appears 
conical  in  shape,  the  apex  being  towards  the  pulp,  the  circular  base 
towards  the  periphery  of  the  dentine.  The  shape  of  the  figure  is, 
no  doubt,  governed  by  the  convergence  of  the  dentinal  tubules, 
which  radiate  from  the  pulp  outwards  in  a  centrifugal  direction.     It 


DENTAL    CARIES 


117 


may  present  the  character  of  hyahne  stripes  or  spots;  and  apparently 
owes  its  existence  to  the  close  approximation  of  the  index  of  refrac- 
tion of  the  dentinal  tubules  and  their  contents  in  this  situation, 
to  that  of  the  matrix  of  the  surrounding  dentine. 

Amongst  the  various  phenomena  of  dental  caries  it  would  be 
difficult  to  find  any  of  greater  interest  or  upon  which  opinions  still 
differ  more  than  the  nature  of  this  "translucent  zone."     It  is  not 


Fig.  133. — A  further  stage  of  caries  of  the  enamel.  Similarly  prepared  and 
lettered  to  the  preceding.  Magnified  45  times.  The  large  cavity  is  easily 
recognised. 


always  found  in  carious  dentine,  and  sometimes  it  exists  in  places 
where  there  is  not  a  trace  of  the  condition. 

Two  main  opinions  are  still  held  regarding  its  production.  Thus, 
Sir  John  Tomes  and  Miller,^  with  Magitot,^  and  others,  considered 
it  due  to  vital  action  on  the  part  of  the  dentine,  which  leads  to  a 
calcification  of  the  dentinal  fibril. 

1  "Micro-organisms  of  the  Human  Mouth,"  1889. 

2  "Traite  de  la  Carie  des  Dents,"  1867. 


ii8 


THE    DENTAL   TISSUES 


And  secondly  Wedl,^  Black,^  Leber  and  Rottenstein,^  C.  S.  Tomes, 
F.  J.  Bennett/  and  Abbott,  regard  it  as  an  area  of  partial  decalcifica- 
tion, with  obliteration  of  the  dentinal  tubules  by  swelling  of  the  basis 
substance.  Bennett  says  that  enlarged  and  thickened  tubules  can 
be  demonstrated  in  parts  {loc.  cit.  p.  162). 


PE 


PE 


PE 


PD 


Fig.  134- — An  early  stage  of  decalcification  of  the  dentine.  Prepared  by 
grinding.  Unstained.  Magnified  25  times,  p.e.  Carious  enamel;  p.d.  Pigmen- 
tation area  in  dentine;  d.   Normal  dentine. 

The  Vitalists'  arguments  cannot  be  put  entirely  out  of  court  be- 
cause there  is  no  doubt  that  dentine  is  endowed,  more  or  less,  with 
a  modified  form  of  vitality.     The  chief  points  are  these:— 

{A)     The  zone  does  not  form  in  "dead"  teeth. 

1  "Pathologie  der  Zahne,"  1870. 

'-=  "American  System  of  Dentistry,"  1887. 

^  "Caries  der  Zahne,"  1867. 

*  Trans.  Odonto.  Soc.  of  Great  Britain,  1895. 


DENTAL   CARIES 


119 


Miller  examined  both  macro-  and  micro-scopically  teeth  which 
had  been  worn  on  plates,  and  he  never  found  one  specimen  which 
gave  signs  of  the  zone.  A  large  number  were  subjected  to  the  naked 
eye  test,  while  about  a  dozen  different  "dead"  teeth  were  ground 
down  and  examined  microscopically. 

(B)  The  zone  is  seen  in  cases  where  enamel  has  undergone  attri- 
tion and  where  caries  is  absent. 

(C)  Narrow  bands  of  translucent  dentine  sometimes  extend  even 
to  the  pulp  chamber.  This  is  never  the  case  with  decalcification, 
which  proceeds  through  the  tissues  in  a  fairly  regular  line. 


Fig.  135. — A  further  extension  of  caries,  showing  penetration  to  the  cortex 
of  the  dentine  of  the  carious  cavity.  Prepared  by  grinding.  Unstained.  Mag- 
nified 20  times,     c.  Carious  enamel;  CD.  Carious  dentine. 


(D)  The  chemical  analysis  of  the  dentine  in  the  translucent  zone 
•does  not  yield  results  at  all  compatible  with  the  decalcification  theory. 
Normal  and  translucent  dentine  were  tested;  the  former  yielded 
72.1  per  cent,  of  lime  salts;  the  latter  71.9  per  cent.,  a  difference, 
.as  Miller  pointed  out,  quite  within  the  limits  of  the  errors  of  ex- 
periment. Jeserich  analysed  the  translucent  and  normal  dentine  of 
twenty  teeth,  and  his  experiments  showed  that  the  former  contained 
69.5  per  cent,  and  the  latter  68  per  cent,  of  lime  salts.  These  results 
•do  not  indicate  any  decalcification. 


I20 


THE    DENTAL    TISSUES 


{E)  The  zone  is  difficult  to  stain  with  eosin,  fuchsine,  and  other 
anihne  dyes;  whereas  decalcified  dentine  is  easily  coloured  by 
similar  re-agents. 

{F)     The  zone  cannot  be  produced  in  vitro. 


Pig.  136. — A  further  extension  of  the  carious  process  in  dentine.  Most  of 
the  enamel  was  removed  during  the  act  of  grinding  the  section.  Unstained. 
Magnified  12  times.  E.  Enamel;  d.  Dentine;  c.  Cavities  produced  by  caries; 
CD.  Carious  dentine,  the  tubes  of  which  are  infected  by  micro-organisms; 
D.D.   Decalcified  dentine;  p.z.  Pigmentation  zone  of  decalcified  dentine. 

In  addition,  Walkhoff  deliberately  asserts  that  there  is  a  diminu- 
tion in  size  of  the  calibre  of  the  tubules,  as  well  as  in  the  diameter  of 
the  fibrils. 

Wellauer  says  that  there  is  a.  contraction  of  the  lumen  of  the 
tubule;  and  Baume,  that  this  contraction  leads,  in  time,  to  absolute 
obliteration  of  the  tubules.        , 


DENTAL    CARIES 


121 


On  the  other  hand,  the  Devitalists  hold  that: — 

{A)  The  zone  is  found  in  "dead"  natural  teeth  which  have  been 
subsequently  attacked  by  caries,  after  they  have  been  mounted  on  a 
plate  and  worn  in  the  mouth  for  some  time : 


PD 


T  Z 


Fig.  137. — Translucent  zone  in  dentine,  cut  obliquely.  Prepared  by  decal- 
cification in  hydrochloric  acid,  stained  with  Ehrlich's  acid  hsematoxylene. 
Magnified  35  times,  e.  Enamel;  a.  Amelo-dentinal  junction;  d.  Non-carious 
dentine;  T.z.  Translucent  zone;  p.d.  Oblique  patch  of  pigmented  decalcified 
dentine. 

(B)  It  exists  in  cases  of  partial  arrest  of  caries  in  teeth,  where  it 
might  be  easily  supposed  that  calcification  of  the  fibrils  and  tubules 
was  actually  taking  place : 

(C)  The  tubules  in  the  zone  are  rather  enlarged  and  thickened, 
presenting  "pipe-stem"  appearances. 

Further,  Leber  and  Rottenstein  state   that  it  is  softer  than  the 


122 


THE   DENTAL   TISSUES 


normal  surrounding  dentine;  and  Wedl  proved  the  patency  of  the 
tubules  in  the  zone  by  immersing  in  a  solution  of  carmine  several 
dried  sections  of  the  transparent  roots  of  senile  teeth.  The  stain 
passed  up  the  tubules  quite  easily. 


Fig.  138. — Extensive  caries  of  the  coronal  region  of  a  human  canine  tooth. 
Prepared  by  grinding.  Unstained.  Magnified  30  times,  e.  Enamel;  r. 
Brown  striag  of  Retzius;  S,  Lines  of  Schreger;  d.  Dentine;  Ci.  Carious  cavities  on 
labial  aspect  of  the  tooth  extending  laterally  and  undermining  the  enamel; 
C2.  The  same  on  the  lingual  surface;  p.  Pulp  cavity.  The  enamel  has  not  been 
fractured  during  the  act  of  grinding  the  section. 


The  arguments  and  theories  on  either  side  are  very  cogent, 
and  one  cannot  say,  in  the  present  state  of  knowledge,  which  is 
correct.  But  it  is  interesting  to  know  that  similar  appearances  have 
been  found  in  cases  of  attrition  and  erosion  of  the  teeth. 


DENTAL   CARIES 


123 


CD 


Fig.  139. — Coronal  section  of  a  human  premolar,  with  extensive  caries  of 
enarael  and  dentine.  The  section  is  rather  thick  in  order  to  retain  the  enamel 
in  situ  without  fracture.  Prepared  by  grinding.  Unstained.  Magnified  15 
times.  E.  Normal  enamel;  c.e.  Carious  enamel;  r.  Brown  striae  of  Retzius; 
D.  Normal,  but  very  pigmented  dentine;  p.  Pulp  cavity;  s.e.  "  Secondary  enamel 
decay; "  CD.  Carious  dentine;  d.d.  Disintegrating  dentine  in  cavity  on  the  buccal 
aspect  of  the  tooth. 


124 


THE    DENTAL    TISSUES 


S  ED 


CD 


C  C 


Fig.  140. — Sagittal  section  of  a  human  incisor  tooth.  Similarly  prepared 
and  magnified  as  the  preceding,  c.  Carious  cavity  with  deep  pigmentation  of 
the  dentine,  on  ths  lingual  aspect  of  the  tooth;  c.C.  Carious  cavity  extending 
towards  the  mesial  and  distal  sides  of  the  tooth;  c.p.  Cornu  of  pulp  which  has 
undergone  calcification;  s.e.d  "Secondary  enamel  decay;"  CD.  Caries  of  the 
dentin;  extending  in  a  lat  ral  direcion. 


DENTAL    CARIES 


12^ 


Fig.  141. — Sagittal  section  of  a  human  incisor  tooth.  Prepared  by  grinding. 
Unstained.  Magnified  20  times,  e.  Normal  enamel;  Ci.  Carious  cavity  on  the 
labial  surface;  C2.  The  same  on  the  lingual  surface;  L.  Extension  of  cavity  under- 
mining the  enamel;  d.   Carious  dentine. 


126 


THE    DENTAL    TISSUES 


Fig.  142. — Tubular  infection  of  the  dentine  by  micro-organisms.  Prepared 
by  the  decalcification  of  carious  dentine.  Stained  by  Gram's  method.  Magni- 
fied 250  times.     D.  Normal  dentine;  c.t.   Micrococci  in  the  tubules 


CF 


Fig.  143. — Tubular  infection  of  the  dentine,  with  the  formation  of  "lique- 
faction foci."  Prepared  as  in  the  preceding.  Stained  with  Ehrlich's  acid 
haematoxylene.  Magnified  50  times,  d.  Dentine  at  margin  of  cavity,  softened 
and  disintegrated  by  the  action  of  the  micro-organisms;  f.  "Liquefaction  focus" 
running  parallel  with  the  tubes;  f.t.  The  same  running  across  the  tubes;  c.T. 
Carious  infection  of  the  tubules;  c.F.   Coalescence  of  several  small  "foci." 


DENTAL   CARIES 


127 


Ft 


Fig.   144. — Similar  to  the  preceding.     Prepared  and  stained  similarly.     Letter- 
ing similar,     d.d.   Disruption  of  the  dentine. 


Fig.   145. — A  "liquefaction  focus"  from  the  preceding  figure.      Magnified  300 
times.     D.  Deflected  tubes,  mentioned  in  the  text.     See  page  135. 


128 


THE    DENTAL    TISSUES 


Miller  observed  and  described^  the  presence  of  opaque  stripes  or 
zones  which  border  on  the  translucent  zone.  Under  the  microscope 
they  appear  almost  black,  and  the  tubules  in  these  areas  are  found 
full  of  irregular,  angular  granules  or  rod-shaped  elements.  The 
opaque  zones  are  almost  constantly  associated  with  the  transparent 
zones,  and  usually  separate  the  latter  from  the  normal  dentine,  or 
fill  up  the  space  between  the  transparent  zone  and  the  pulp. 

These  differ  from  the  rod-shaped  elements  or  fragments  in  the 
tubules  of  carious  dentine  first  noticed  by  Sir  John  Tomes.     They 


Fig.    146. — Caries  of   dentine.      Magnified  450   times.     M.    Micro-organisms  in 
dentinal  tubes  (pure  infection);  l.f.   "Liquefaction  focus." 


are  often  seen,  and  were  believed  by  their  discoverer  to  be  "portions 
of  consoHdated  dentinal  fibrils,"  or  "bits  of  the  sheaths  of 
Neumann,"  or  "  casts  of  the  enlarged  tubules."  They  are  sometimes 
seen  in  artificial  caries,  and  if  brought  into  contact  with  dilute 
sulphuric  acid  completely  disappear. 

Rows  of  sinning  irregular  granules  are  also  met  with  in  advance 
of  cariesd.  It  is  possible  that  they  have  the  same  origin  as  the  rod- 
shaped  elements  just  alluded  to.  Tomes,  Magitot,  and  others 
described  them  as  "lime-granules,"  while  other  observers  believe 
them  to  have  a  fatty  nature. 

1  "Trans.  Odonto.  Soc.  of  Great  Britain,"  p.  39,  1895. 


DENTAL    CAEIES 


129 


LF 


Fig.    14  . — Similar      to      preceding.      Magnified      450      times,      m.    Micrococci; 
L.F.   "Liqueiac-ion  foci. " 


Fig.  148. — Micrococci  in  the  dentinal  tubes,  from  a  section  of  dentine  in 
which  caries  was  induced  experimentally  in  vilro.  Prepared  by  the  Author's 
method  for  the  production  of  artificial  caries.  Stained  by  Gram's  method. 
Magnified  750  times.  M.  Tubule  infected  by  micro-organisms;  N.  Non-infected 
tubule. 


I30 


THE    DENTAL    TISSUES 


(v)   Tubular  infection  by  micro-organisms  and  formation  of 
"liquefaction  foci" 

Examined  under  a  low  power  (i6  mm.  objective),  a  section  of 
carious  dentine  stained  by  Gram's  method,  appears  of  a  pale  yellow 
colour,  faintly  showing  the  tubules  in  the  unaffected  parts,  and 
lines  of  stain  extending  inwards  from  the  margins  of  the  cavity. 
These  run  in  a  parallel  direction  (see  Fig.  148),  some  passing  through 
the  whole  of  the  tissue,  others  traversing  part  of  the  distance.  In 
addition,  near  the  margin  of  the  cavity,  irregular  spaces  can  be 


Pig.   149.- 


-Micrococci  in  the  dentinal  tubules.      Stained  by  Gram's  method. 
Magnified  550  times. 


found,  in  a  line  with  the  stained  streaks  (Figs.  143  and  144).  These 
spaces  vary  considerably  in  shape  and  size.  They  are  large  and 
irregular  near  the  carious  cavity,  smaller  near  the  pulp.  Here  they 
are  less  irregular,  are  oval  in  shape,  and  are  in  direct  continuity 
with  the  dentinal  tubules  ("Hquefaction  foci.") 

If  now,  a  higher  power  be  used  for  examining  the  section  (0.9  mm. 
homogeneous  immersion  objective),  the  stained  streaks  are  seen  to 
be  composed  of  crowds  of  micrococci  and  bacilH  (see  Figs.  148  and 
149),  and  the  spaces,  in  parts,  empty,  with  disorganised  tissue  at 
their  edges,  and  in  parts  filled  with  micro-organisms.     Of  all  the 


DENTAL    CARIES 


131 


Fig.   150. — Similar  to  the  preceding. 


Fig.    151. — Bacilli    and    micrococci    in    the    dentinal    tubules,     c.   Micrococci; 
B.  Bacilli.      {Pholomicrograph  by  Howard  Mummery.) 


132 


THE    DENTAL    TISSUES 


varieties,  the  spherical  forms  largely  predominate,  either  singly  or 
in  pairs,  or  chains,  or  clusters.  Occasionally  the  tubes  may  contain 
rods,  or  even  threads;  a  mixed  infection  also  is  far  from  uncommon. 
(Fig.  151.) 

Leptothrix  buccalis,  and  other  thread  forms,  with  torulae,  and 
some  micrococci  fringe  the  edges  of  the  carious  cavity,  as  in  Fig.  152. 

Normal  interglobular  spaces  seem  to  afford  a  convenient  locality 
for  the. housing  of  the  germs.  They  (the  germs)  often  spread  in  a 
lateral    direction   via   the   interglobular   spaces;   but   once   having 


Pig.  152. — Thread  forms  of  bacteria  fringing  a  carious  cavity  in  the  dentine. 
Prepared  by  decalcification.  Stained  by  Gram's  method.  Magnified  280 
times.  D.  Carious  dentine;  M.  Mass  of  micro-organisms;  t.  A  tuft  of  thread- 
shaped  micro-organisms. 

passed  them  they  extend  directly  inwards  towards  the  pulp,  by 
means  of  the  tubules. 

All  portions  of  dentine  are  not  affected;  the  boundary  between 
the  infected  and  non-infected  parts  being  very  regular.  This 
zone  is  called  "  the  non-infected  zone,"  and  shows  that  decalcification 
of  dentine  precedes  its  infection  by  bacteria. 

After  the  micro-organisms  have  once  entered  the  tubules,  they 
easily  pass  along  their  lumina.  The  canals  then  become  choked 
with  micrococci,  gradually  enlarge,  and  give  way  in  various  places. 
These  masses  are  called  "liquefaction  foci,"  and  they  correspond 


DENTAL    CARIES 


133 


Fig.   153. — Similar  to  the  preceding.      Rod-shaped  micro-organisms  entering  the 

dentinal  tubes. 


"     ^       •    1_        '  ^x 


^«^ 


Ai.^       ^  ♦  ^  *-  *  *  ♦  *^ 


'%^^ 


.■•^ 


Fig.  154. — The  "pipe-stem"  appearance  of  carious  dentine.  Prepared  as 
in  Fig.  152.  Stained  by  Gram's  method.  Magnified  280  times,  i.  Infected 
tubules;  n.   Non-infected  tube;  m.  Micro-organisms  in  the  matrix  of  the  dentine. 


134 


THE    DENTAL    TISSUES 


to    the   "varicosities   and   globular   swellings"    mentioned   by   Sir 
John  Tomes  in  his  earlier  writings. 

Heider  and  Wedl  ("Atlas  zur  Pathologic  der  Zahne,"  Leipzig, 
1869)  describe  and  figure  enlargement  of  the  dentinal  tubes  which 
possibly  are  undergoing  changes  towards  those  of  "liquefaction 
foci."  Isolated  from  the  dentine  on  the  border  of  the  softened 
carious  portion  by  means  of  dilute  hot  hydrochloric  acid,  they  were 
characterised  by  a  considerable  amount  of  tumefaction,   by  the 


CD 


Fig.   155. — Carious    dentine;    tubes    cut    obliquely.      Magnified   450    times.     D. 
Non-infected  dentine;  CD.   Carious  dentine. 

issuing  from  them  of  short  lateral  branches,  and  by  being  covered 
in  places  with  tiny  clusters  of  globules. 

If  the  enlargement  of  the  tubules  continues,  contiguous  "lique- 
faction foci"  become  fused,  and  a  space  or  cavity  of  an  irregular 
shape  is  produced.  The  dentine  ultimately  becomes  more  and  more 
cavernous,  and  so  is  gradually  broken  up,  and  its  debris  finally 
washed  away  by  the  oral  fluids. 

If  transverse  sections  be  made  near  the  healthy  dentine,  the 
"pipe-stem"  appearance  first  described  by  Tomes  is  visible  (Fig. 
154).  This  is  the  result  of  the  enlargement  and  thickening  of  Neu- 
mann's sheaths.     How  this  enlargement  is  brought  about  is  by  no 


DENTAL    CARIES 


135 


means  understood.  Miller  attributes  it,  to  quote  his  words,  to 
"the  pressure  of  the  fungal  masses  in  the  tubules,  by  which  a  com- 
pression of  the  walls  is  caused." 

The  author  believes  that  the  prominence  of  these  tubules  is 
occasioned  by  two  factors: — (i)  An  actual  enlargement  of  their 
diameters;  and  also  (ii)  An  actual  but  slight  thickening  of  their 
sheaths. 

The  expansion  is  produced  by  pressure  of  the  micro-organisms 
in  an  outward  direction  on  the  peptonised  or  decalcified  dentinal 


Fig.    156. — Similar  to  the  preceding.      Magnified  600  times. 

matrix  (see  Fig.  145).  Sometimes  the  tubules,  as  at  (d),  are 
deflected  in  their  courses  by  the  lateral  enlargement  of  the  "lique- 
faction focus." 

The  thickening  of  the  specially  resistant  walls  is  actually  pro- 
duced by  the  enzymes  of  the  micro-organisms  within,  the  elastin 
which  they  contain,  being  probably  converted  into  immeasurable 
quantities  of  amino-acetic  acid. 


(vi)  Fusion  of  Liquefaction  Foci  and  Production  of  Cavity 

The  pressure  of  the  bacterial  masses  on  the  softened  intervening 
matrix  soon  causes  the  foci  to  amalgamate.     In  process  of  time  a 


136 


THE    DENTAL    TISSUES 


Fig.    1.157. — Similar  to  the  preceding,  but  the  tubules  are  cut  obliquely 
Magnified  600  times. 


Fig.    158. — Similar  to  the  above,  but  the  tubules  are  cut  slightly  obliquely. 
Magnified  280  times. 


DENTAL    CARIES 


137 


cavity  is  formed  by  the  coalescence  of  many  foci,  its  contents  being 
of  a  soft  cheesy  consistency,  and  crowded  with  micro-organisms. 
The  walls  of  the  cavity  become  extended  by  the  rapid  multiplication 
and  peptonising  action  of  bacteria,  and  the  final  stages  are  reached  by 
the  undermining  and  subsequent  fracture  of  the  walls  (Fig.  162). 
An  attempt  has  been  made  in  the  accompanying  photomicrographs 
to  illustrate  these  various  stages. 


^-fi*; '«'      «*. 


.<. 


'.■^ 


Fig.   159. — Round   and   rod-shaped  bacteria  in  the  matrix  of  carious  dentine. 
Stained  by  Gram's  method.      Magnified  600  times. 


(vii)  Caries  of  the  Cementum 

Caries  of  the  cementum  is  less  common  than  that  of  enamel  or 
dentine.  It  can  be  well  observed  on  the  exposed  surface  of  the 
palatine  roots  of  maxillary  molars  when,  through  septic  infection, 
these  have  been  denuded  of  their  alveolar  sockets  and  periodontal 
membranes. 

The  microscopical  appearances  are  interesting,  because  they  show 
that  the  micro-organisms  gain  admission  to  the  short  canals  occupied 
by  the  penetrating  fibres  of  Sharpey,  and  cause  their  contents  to 
swell.  It  proves  that  these  fibres  fill  these  bony  channels  somewhat 
similarly  to  the  fibrils  in  the  dentinal  tubules.  Probably  the  process 
of  caries  in  cementum  is  not  quite  analogous  to  that  in  dentine.     In 


T> 


138 


THE   DENTAL   TISSUES 


consequence  of  its  close  association  with  the  periodontal  membrane, 
the  condition  is  usually  checked  in  advancing  at  the  border  of  the 
tissue.  Roots  of  teeth  are  often  seen  in  which  the  dentine  has 
nearly  all  disappeared,  merely  a  thin  shell  of  cementum  being  re- 
tained in  situ.  The  real  reason  of  this  would  appear  to  be  accounted 
for  by  the  absence  of  tubes  or  lacunse  in  the  homogeneous  layer  of 
the  dentine  the  non-tubularity  thus  prohibiting  here  the  admission 
of  micro-organisms. 

]     (viii)  "Arrested"  Caries 

Little  is  known  of  the  physical,  chemical,  and  histo-pathological 
changes  which  bring  about  this  condition.     In  the  enam.el,  pigmen- 


FiG.    160. — Masses  of  micro-organisms  in  the   matrix  of  very  carious  dentine. 
Staining  and  magnification  as  in  the  preceding  figure. 


tation  extending  inwards  to  varying  depths  is  noticed;  the  inter- 
columnar  substance  is  well-defined;  the  rods  themselves  present 
a  homogeneous  appearance.  The  brown  strise  of  Retzius  and 
Schreger's  lines  may  or  may  not  be  entirely  obliterated  (see  Fig. 
200).  In  the  dentine,  the  circumferential  tubes  are  occluded,  the 
refractive  indices  of  tubes  and  matrix  thus  approximating.  In  the 
pulp,  adventitious  dentines  of  one  or  more  types  may  generally 
be  found. 


DENTAL   CARIES 


139 


(ix)   The  Micro-organisms  of  Dental  Caries, 

The  micro-organisms  normally  found  in  the  human  oral  cavity 
are  of  all  kinds:  cocci  occur  most  abundantly,  but  also  baciUi 
thread-forms,  sarcinae  and  spirilla.  It  is  probable  that,  of  the  first 
named  the  Streptococcus  viridans,  the  Staphylococcus  pyogenes  aureus 
and  the  Diplococcus  pneumonia  are  the  commonest  of  the  patho- 
genic varieties.  In  addition  many  aerobic  and  anaerobic  spore- 
forming  bacilh  are  taken  in  through  the  media  of  air,  food,  and 
water  (see  Chapter  XVI). 


A  D 


Pig.   161. — Enamel    in    "arrested    caries."      Magnified    90    times,     e.   Carious 
enamel;  a.d.   Amelo-dentinal  junction;  D.   Normal  dentine. 

It  is  difficult  to  determine  with  any  degree  of  accuracy  the  mor- 
phological and  biological  characteristics  of  the  actual  producers  of 
dental  caries;  it  is  so  extremely  easy,  even  with  the  utmost  care, 
to  obtain  bacteria  for  experimental  purposes  that  are  incapable 
of  causing  the  initial  decalcification  of  the  enamel.  Nor  is  it  yet 
ascertained  whether  the  bacterial  factors  which  may  occasion  the 
dissolution  of  the  peripheral  hard  parts  of  the  teeth  are  the  same  as 
those  inhabiting  the  dentinal  tubules,  or  the  surfaces  of  carious 
cavities.  The  saliva  carries  with  it,  and  sweeps  into  such  cavities, 
adventitious  bacteria.     Others  from  the  oral  mucous  membrane,  the 


140  THE    DENTAL    TISSUES 

gingival  troughs,  the  alveolar  "pockets,"  the  tonsils  and  pharynx, 
add  their  quota  to  the  varieties  of  the  oral  flora  and  make  real 
discrimination  between  the  caries-producing  and  the  non-caries- 
producing  organisms  very  difiicult.  On  microscopical  examination 
of  a  fragment  of  carious  enamel  or  dentine,  multitudes  of  bacteria  are 
observed:  but  it  is  almost  impossible  to  affirm  with  certainty  whether 
those  present  are  such-and-such  organisms.  Identification  is 
often  impossible.  The  bacteria  of  caries  as  Goadby^  points  out 
appear  to  be  influenced  very  largely  by  their  environment;  and  it  is 
quite  possible  that  the  actual  producers  of  the  dissolution  of  the 
enamel  are  often  overwhelmed  by  the  preponderating  growth  of 
others,  which,  as  secondary  agents  of  "dental  decay,"  penetrate  the 
dentinal  tubules  and  peptonise  their  walls. 

Several  facts,  however,  would  seem  to  stand  out  pre-eminently. 
The  bacteria  in  superficial  parts  are  aerobic;  those  beneath,  in  the 
vanguard  of  the  advancing  host,  anaerobic  or  facultative  aerobic; 
many  as  yet,  cannot  be  cultivated  on  the  ordinary  laboratory  media; 
the  superfically  placed  bacteria  produce  proteolytic  enzymes,  others 
fermentation  with  acid  production;  no  liquefaction  of  undecalci- 
fied  dentine  takes  place  by  means  of  the  proteolytic  enzymes;  and 
finally  it  is  practically  impossible  to  differentiate  between  pathogenic 
and  non-pathogenic  forms.  For  according  to  Emery  ("Immunity 
and  Specific  Therapy,"  1909),  "any  bacterium  will  produce  disease 
if  it  grows  in  the  tissues  of  the  hving  body,  and  all  bacteria — those 
growing  only  at  very  high  or  very  low  temperatures  or  on  media 
very  poor  in  nitrogen  perhaps  excepted — will  do  so  if  the  necessary 
degree  and  form  of  immunity  is  not  present." 

As  far  as  is  at  present  ascertained,  it  may  be  briefly  stated  that 
the  micro-organisms  found  in  the  superficial  parts  of  carious  dentine 
are  either  liquefiers  of  that  tissue,  when  it  has  already  been  decalcified 
to  a  certain  extent,  or  are  merely  enzyme  producers.  To  the  former 
^roup  belong,  in  alphabetical  order, _  the  Bacillus  furvus,  Bacillus 
gingivcB  pyogenes,  Bacillus  liquefaciens  fluorescens  motilis,  Bacillus 
mes enter icus  f us cus,  ruber,  and  vulgatus.  Bacillus  plexiformis,  Bacillus 
suhtilis,  and  Proteus  vulgaris;  to  the  latter  the  Sarcina  alba,  auran- 
iiaca  and  lutea,  Staphylococcus  albus  and  aureus,  and  Streptococcus  ■ 
viridans.  Those  isolated  from  the  deeper  layers  of  carious  dentine 
are  the  Bacillus  necrodentalis,  and  Staphylococcus  albus.  A  third 
class  includes  the  chromogenic  bacteria.  Fringing  the  edges  of 
carious  surfaces  are  many  thread-like  organisms.     These  often  in- 

1  "The  Mycology  of  the  Mouth,"  1903. 


DENTAL    CARIES  I4I 

elude  Leptothrix  innominata,  Leptothrix  huccalis  maxima,  Streptothrix 
buccalis,  and  the  curved  and  spiral  forms  described  as  the  Spirillum 
sptikigenum,  and  Spirochcete  dentium. 

EPITOME    OF    MICROSCOPICAL   APPEARANCES    OF    CARIES 

-    I.  iVa5wv//? '5  Memftrnwe  shows  mere  pigmentation. 

2.  Ename!. — The   rods   are   separated;    their   striae   pronounced; 


Fig.  162. — Final  stages  in  the  destruction  of  carious  dentine.  Prepared  by 
decalcification.  Unstained.  Magnified  40  times.  D.  Carious  dentine;  p. 
Pulp  cavity. 

are  granular,  and  broken  down.  Bacteria  pass  between  them  and 
take  their  place  in  "secondary  enamel  decay."  Three  zones  are 
present,  viz.,  those  of  partial  decalcification,  complete  decalcifica- 
tion, and  "secondary  enamel  decay." 


142  THE   DENTAL   TISSUES 

3.  Dentine. — Tubules  filled  with  micrococci  and  bacteria;  "lique- 
faction foci"  are  formed.  "Tobacco-pipe  appearances"  and  "Zone 
of  translucency"  are  noticed.  The  opaque  zones  of  Miller 
frequently  exist.  In  some  places  rod-shaped  fragments  fill  the 
tubules.     Homogeneous  layer  usually  non-infected. 

4.  Cemenium. — Fibres  of  Sharpey  are  attacked  by  micro-organ- 
isms, the  dentinal  surface  meanwhile  unaffected. 


CHAPTER  V 
THE  DISEASES  OF  THE  DENTAL  PULP 

Microscopical  Elements  in:— (i)  Hyperaemia;  (ii)  Acute  and  Chronic 
Inflammation;  (iii)  Infective  Gangrene  of  the.  Pulp;  (iv)  The 
Pathogeny  of  Gangrene  of  the  Pulp. 

GENERAL   CHARACTERISTICS 

In  nearly  every  case  of  dental  caries  there  are  certain  morbid  proc- 
esses found  in  connection  with  the  dental  pulp.  The  majority  of 
the  pathological  conditions  met  with  in  this  organ  are  due  to  causes 
operating  from  the  outside,  only  a  few  being  determined  by  and 
dependent  on  endogenetic  disturbances. 

Miology.— The  causes  of  diseases  of  the  dental  pulp  generally 
may  be  classified  as  (A)  Predisposing,  (B)  Exciting. 

(A)  Predisposing  Causes.— (i)  General:  (a)  Physiological,  e.g.: 
Heredity,  age,  sex;  (b)  Pathological,  e.g.:  Marasmus,  long-con- 
tinued fevers,  gout  and  similar  dyscrasia;  (2)  Local:  Anatomical 
peculiarities  of  the  dental  tissues. 

(B)  Exciting  Causes. — (i)  General:  Effects  of  disease  of  (a)  Vas- 
cular system,  e.g.:  Anemia,  chlorosis,  gout,  etc.,  and  (b)  Nervous 
system,  e.g.:  Neurasthenia,  etc.;  (2)  Local:  (a)  Apparent— Effects 
of  dental  caries;  (b)  Non-apparent— Thermal,  chemical,  and 
electrical  stimulations,  etc. 

It  is  extremely  probable  that  morbid  affections  of  Nasmyth's 
membrane  or  enamel  per  se  (both  products,  as  already  described  in 
Chapters  II  and  XII,  Vol.  I,  of  the  stomodaeal  ectoderm)  exert  some 
unknown  influence  on  the  subjacent  tissues.  This,  and  the  two  fol- 
lowing Chapters,  however,  are  concerned  with  the  variations  that  take 
place  in  the  pulp  at  periods  of  time  antecedent  and  posterior  to  the 
carious  penetration  of  its  containing  cavity:  as  also  the  histological 
elements  in  the  pathogenic  changes  it  undergoes  through  traumatic 
and  degenerative  lesions. 

It  is  necessary,  at  the  outset,  to  again  remind  the  student  of  the 
fact  that  the  pulp  has  no  pathology  peculiar  to  itself.  It  shares 
with  other  organs  of  a  highly  vascular  nature  phenomena  of  an 

143 


144  THE    DENTAL    TISSUES 

identical  kind,  differing  mainly  in  the  particulars  that  it  is  enclosed 
in  a  bony  casing  which  prevents  much  inflammatory  exudation,  or 
swelling.  This  confinement  in  hard  unyielding  walls  probably  pre- 
vents, in  no  slight  degree,  the  tendency  for  an  exposed  pulp  to  cica- 
trize, and  induces,  in  the  majority  of  cases  of  acute  inflammation,  the 
death  of  the  pulp  in  part  or  in  whole. 

Peripheral  carious  stimulation  of  the  dentine  is  accompanied  by 
destructive  as  well  as  constructive  metamorphoses;  tissue  waste  and 
tissue  repair  go  on  side  by  side.  At  first  the  soft  parts  alone  suffer; 
the  dentinal  fibrils  and  their  enclosing  tubules,  in  parts  of  their 
courses,  are  affected  and  soon  become  disorganised,  the  blood-vessels 
and  tissues  of  the  pulp  meanwhile  undergoing  hyperasmic  and  other 
changes.  Thus  a  superficial  carious  patch  beneath  the  cortex  of  the 
enamel  is  associated  with  marked  cellular  activity  on  the  part  of  the 
pulp;  while  there  is  a  loss  of  substance  externally,  there  is  a  gain  in- 
ternally. This  is  exemplified  in  the  formation  in  certain  circum- 
stances of  "dentine  of  repair."  In  other  words,  caries,  even  in  its 
early  stages,  usually  leads  to  a  deposit  of  new  adventitious  dentine 
on  the  surface  of  the  pulp. 

But,  later  on,  bacterial  agencies  multiply  and  accumulate; 
advancement  renders  them  still  more  potent;  and  development 
means  destruction.  For  now  not  only  do  the  dentinal  tubules  and 
matrix  also  become  involved  in  the  general  dissolution,  but  any  ad- 
ventitious tissues  that  may  have  been  developed,  rapidly  break 
down,  and  soon  the  work  of  demolition  is  complete.  A  study  of 
these  phenomena  possesses  many  points  of  profound  interest. 

Hypercemia  of  the  Pulp 

This  condition  is  analogous  in  all  respects  with  active  or  arterial 
hyperaemia  and  passive  or  venous  hyperaemia  occurring  in  other  soft 
tissues  of  the  body.  It  may  be  partial  or  complete — confined  to 
one  of  the  cornua  or  the  coronal,  cervical,  or  radicular  portions  of 
the  pulp  cavity,  or  distributed  throughout  the  whole  of  the  soft 
tissue.  It  is  probably  dependent,  in  the  first  instance,  on  irritation 
of  the  dentinal  fibrils,  produced  by  various  causes,  and  may  pass 
quickly  on  to  acute  hyperaemia  and  inflammation  of  the  pulp.  If 
has  been  called  ''Irritation  of  the  pulp,"  an  incorrect  appellation,  for 
irritation  is  the  cause,  not  the  actual  disease.  The  first  change  from 
normal  to  an  abnormal  state  of  the  pulp  is  not  irritation  but  hyperae- 
mia— if  slight  it  is  usually  regional,  if  intense  diffuse. 


DISEASES    OF    THE    DENTAL    PULP  1 45 

Etiology. — Any  factor  that  determines  an  increase  of  the  flow  of 
blood  in  the  tissue  is  the  cause  of  hyperaemia.  Thus  it  may  be 
ascribed  to: — (i)  Caries,  (ii)  Injury  to  the  dentine,  which  sets  up 
dentinal  irritation,  (iii)  Early  stages  of  cold,  (iv)  Rheumatic  affections 
of  the  jaws,  and  (v)  possibly  Hydrargyrism. 

Secondary  Changes. — Resolution  or  inflammation,  most  com- 
monly the  latter. 

GENERAL   CONSIDERATIONS 

The  nutritional  well-being  of  the  pulp  depends  upon  the  proper 
regulation  of  its  blood  supply,  which  is  governed  by  the  influence 
of  the  sympathetic  nerves  of  the  unstriated  muscle  fibres  in  the  walls 
of  the  arteries,  the  elastic  tissue  in  the  tunica  media  of  the  vessels 
maintaining  simultaneously  the  necessary  "  tone. "  When  the  usual 
amount  of  blood  exceeds  this  physiological  limitation,  pathological 
hyperasmia  is  induced  and  may  be  (A)  Active  or  arterial,  or  (B) 
Passive  or  venous,  according  to  which  set  of  vessels  are  most  chiefly 
affected. 

(A)  Arterial  hyperaemia  may  be  induced  by  any  condition  which 
either  (i)  paralyzes  the  vaso-constrictor  nerves  or  (ii)  stimulates  the 
vaso-dilator  nerves,  or  (iii)  weakens  the  tunica  media  or  (iv)  removes 
the  extra-vascular  pressure.  All  these  factors  may  act  singly  or  in 
concert  with  one  another. 

If  a  sufficiently  large  area  of  dentine  has  been  exposed  during 
the  course  of  dental  caries,  various  forms  of  irritation  may  set  up  a 
localized  regional  hyperaemia.  Such  forms  of  irritation  are  the 
chemical  or  bio-chemical  products  of  decomposition  of  liquid  or 
soft  food,  vitiated  oral  secretions,  thermal  changes  in  the  mouth, 
and  drugs  medicinally  or  artificially  applied  for  therapeutic  purposes. 
Cold  paralyzes  the  vaso-constrictor  nerves;  heat,  the  vaso-dilators, 
while  the  alteration  of  the  protoplasmic  contents  of  the  dentinal 
tubes  by  the  products  of  bacteria  and  the  use  of  chemical  reagents 
probably  weakens  the  vessel  walls. 

(Bj  Passive  or  venous  hyperaemia  occurs  much  more  frequently 
than  arterial  hyperaemia.  It  is  due  to  an  abnormal  obstruction 
to  the  outflow  of  blood  from  the  veins  of  the  pulp,  being  dependent 
upon  local  conditions.  The  obstruction  is  generally  at  the  apical 
portion  of  the  roots  of  the  teeth,  where  the  mechanical  unyielding 
of  the  hard  dentinal  walls  combined  with  the  absence  of  a  collateral 
circulation  causes  its  development  to  the  fullest  degree. 

The  microscopical  changes  in  the  pulp  affected  by  venous  conges- 


146  THE   DENTAL    TISSUES 

tion,  which  will  be  presently  fully  described,  may  be  summarized 
as  follows: — A  capillary  and  venous  dilatation  is  followed  by  the 
organ  becoming  deeply  reddened;  the  axial  and  peripheral  blood 
streams  in  the  veins  become  confused;  the  erythrocytes  are  densely 
crowded  together;  and  stasis  (the  cessation  of  flow  of  the  blood 
current)  and  emigration  of  the  colourless  blood  cells  supervene. 
The  dilatation  of  the  capillaries  and  veins  arises  from  the  loss  of 
balance  of  the  haemodynamic  pressure  caused  by  the  lessened  resist- 
ance of  the  blood  stream  to  friction,  through  its  slowing  down.  A 
transudation  of  liquor  sanguinis  through  the  endothelial  walls 
is  favoured  and  accelerated  by  the  intra- vascular  pressure;  and  more 
or  less  oedematous  conditions  quickly  ensue,  because  of  the  absence 
of  lymphatic  vessels  from  the  pulp.  If  these  conditions  remain 
unrelieved,  acute  inflammation  takes  place. 

SPECIAL    HISTOLOGY 

Viewed  from  a  clinical  aspect,  it  may  be  stated  that  the  com- 
mencement of  caries  is  marked,  as  a  rule,  by  one  of  two  distinct 
types  of  lesions:  (i)  the  not  uncommon  clean-cut  cavity,  which 
by  its  general  appearance  suggests  erosion  of  the  enamel  and  dentine; 
and  (2)  the  usual  cavity  of  "  decay."  The  former  is  distinguished  by 
its  position  on  the  cervical  portion  of  the  labial  aspect  of  the  anterior 
teeth,  and  by  its  intense  hyperaesthesia  on  receiving  interrupted 
tactile  impressions;  the  latter  is  recognised  by  its  inability  to  trans- 
mit shght  functional  impulses  to  the  pulp.  Microscopically  the 
difference  between  these  two  classes  is  well  defined,  the  first-named 
particularly  presenting  marked  deviations  from  the  usual  type. 

(i)  The  sub-enamel  region  of  the  dentine  contains  not  only 
the  usual  dentinal  tubes  but  also  areas  occupied  by  large  inter- 
globular spaces,  which  are  distributed  with  more  or  less  regularity 
throughout  its  substance.  Micro-organisms  are  present  in  enormous 
numbers  at  the  margin  of  the  cavity,  and  fill  the  tubules  for  varying 
distances.  Opposite  the  breach  of  surface  a  corresponding  deposit 
of  adventitious  dentine  with  enlarged  irregular  tubules  is  observed. 
The  dentogenetic  zone,  that  layer  of  tissue  "on  the  borderland  of 
calcification"  is  increased  in  thickness,  and  exhibits  a  greater 
quantity  of  calco-globular  masses  than  normally.  They  are,  how- 
ever, very  small.  In  the  pulp,  slight  hyperaemia  and  cell  prolifera- 
tion have  certainly  occurred  in  this  locality  and  its  neighbourhood; 
and  the  peripheral  cells,  which  present  many  of  the  appearances 


DISEASES    OF    THE    DENTAL    FULP 


147 


of  the  so-called  odontoblasts,  are  multiplied  greatly.  Beyond,  the 
tissues  may  be  considered  to  be  normal,  with  the  exception  perhaps 
of  the  smaller  blood-vessels,  whose  lumina  are  more  or  less  increased 
in  size.  Rounded  cylindrical  deposits  of  newly  formed  but 
uncalcified  dentine  constantly  exist  in  the  central  portions  of  the 


D    ; 


Fig.  163. — Hypergemia  of  the  pulp  in  situ.  Prepared  by  the  Author's  process. 
Stained  with  Ehrlich's  acid  haematoxylene.  Magnified  50  times,  p.  Pulp 
tissue;  i.t.  Inflammatory  products;  b.  Enlarged  blood-vessels;  o.  Odontoblasts 
D.  Dentine. 

pulp,  and  point  to  a  degenerative  process.  The  changes  from  the 
normal  to  the  pathological  areas  are  very  gradual,  no  sharp  hne  of 
demarcation  cutting  them  off  from  the  other  parts  of  the  soft 
tissues. 

Referring  to  the  statement  just  enunciated  that  ''the  so-called 


I  T 


148  THE    DENTAL    TISSUES  ■ 

odontoblasts  are  multiplied  greatly,"  it  must  not  be  inferred  that 
these  cells  are  merely  numerically  increased.  They  are  profoundly 
modified,  inasmuch  as  they  now  possess  certain  new  characteristics. 
Their  nuclei  have  become  elongated  and  flattened,  and  are  rendered 
very  prominent  when  any  of  the  nuclear  stains  have  been  used,  and 
perhaps  they  are  more  granular  than  usual.  The  cell  walls  are 
indistinguishable,  chiefly  from  the  fact  that  each  odontoblast  is 
compressed  laterally  by  its  neighbours.  In  some  instances  they  are 
gathered  into  sheaves,  as  in  fibroid  degeneration  or  atrophy  of  the 
pulp.  Some  observers  might  describe  the  appearances  as  being  due 
to  an  indirect  splitting-up  of  the  cells:  and  it  is  not  difficult  to  con- 
ceive of  an  odontoblast,  when  once  fully  formed,  undergoing  mitotic 
changes.  In  sections  prepared  by  Weil's  method,  microscopically 
the  tubules  in  the  primary  dentine  below  the  breach  of  surface 
are  unaffected  by  stains,  and  clearly  differentiated  from  other  tubules, 
having  been,  perhaps,  fully  calcified  throughout  their  extent,  and  a 
band  of  altered  pulp  tissue  may  extend  right  across  that  organ. 

Thus,  at  the  very  outset,  two  most  remarkable  conditions  attract 
attention.  These  are  the  multiplication  of  the  numbers  of  inter- 
globular spaces,  and  also  cytogeny  of  the  so-called  odontoblast  cells — ■ 
phenomena  which  are  entirely  absent  from  all  ordinary  conditions. 
There  would,  therefore,  seem  to  be  some  connection  between  the 
subjective  symptoms  of  pain  and  these  fresh  developments — or  at 
all  events  one  of  these  fresh  developments — and  this  leads  one  to  the 
conclusion  that  the  degree  of  the  sensitiveness  of  these  cavities  is 
dependent  partly  on  the  increase  or  diminution  in  the  numbers 
of  the  interglobular  spaces,  and  partly  on  the  anatomical  relation- 
ships which  hitherto  existed  between  the  hard  tissues.  The  author 
believes  that  the  sensitiveness  of  these  marginal  cavities  is  due,  in  a 
great  measure,  to  the  actual  exposure  of  the  terminations  of  the 
dentinal  fibrils,  which  is  associated  with  that  developmental  error 
where  the  edge  of  the  enamel  and  cementum  do  not  meet,  as  they 
normally  do  houi  a  bout. 

Bodecker/  in  speaking  of  dentinal  irritation  in  the  case  of  ordinary 
caries,  attributes  the  sensations  of  pain  to  "alternate  contractions 
and  expansions  of  living  matter"  in  dentine  and  enamel,  "conveyed 
from  the  periphery  to  the  centre  of  the  tooth,  these  intense  contrac- 
tions being  induced  by  highly  irritating  agencies." 

But  it  must  be  remembered  that  it  is  only  mechanical  stimulation, 
at  first,  of  the  floor  of  these  particular  cavities  that  gives  rise  to  pain; 

^  "Anatomy  and  Pathology  of  the  Teeth,"  p.  288,  1894. 


DISEASES    OF    THE    DENTAL    PULP 


149 


and  it  must  be  inferred  with  greater  accuracy  in  the  light  of  present 
knowledge  of  the  physiological  stimulation  of  nerves  and  protoplasm 
generally,  that  the  pathic  disturbances  are  due  here  to  direct  impulses, 
which  pass  by  means  of  the  dentinal  fibrils  from  the  protoplasmic 
contents  of  the  interglobular  spaces  to  the  ultimate  telodendria 
of  the  sensory  pulp  neurones. 

The  occurrence  of  additions  to  the  numbers  of  the  long  odontoblast 
cells  does  not  admit  of  quite  so  easy  an  explanation.  The  writer ^ 
just  quoted  has  indirectly  noticed,  although  he  has  not  figured 


B  w 


Fig.  164. — Odontoblasts  in  acute  inflammation  of  the  pulp.  Prepared 
similarly  to  the  preceding.  Magnified  230  times,  o.  Odontoblasts;  d.  Dentine; 
B.w.   Basal  layer  of  Weil;  p.   Pulp  tissue. 


this  phenomenon.  He  says: — "The  first  change  in  the  affected 
pulp-tissue  is  its  reduction  to  an  embryonal  or  protoplasmic  state" 
— a  statement  which  is  certainly  not  verified  on  examination  of 
properly  stained  microscopical  preparations.  Further,  he  proceeds : — 
"Should  the  lymph-tissue  be  reduced  to  its  embryonal  conditions 
as  above  indicated,  the  protoplasm  present  before  transformation 
into  basis-substance  reappears,  and  may  break  up  into  odontoblasts 
or  into  osteoblasts.  In  the  former  case,  the  result  of  irritation  of  the 
pulp-tissue  will  be  dentine,  in  the  latter  bone."     The  method  of  tlius 

1  Op.  cii. 


I50 


THE    DENTAL    TISSUES 


interpreting  the  genesis  of  these  hme-bearing  cells  is  crude  and 
illogical. 

The  local  increase  in  the  numbers  of  the  odontoblasts  may  demon- 
strate that,  in  certain  situations,  there  is  a  greater  need  for  the  higher 
and  more  sustained  exercise  of  their  functions,  these  functions, 
probably,  consisting  mainly  of  shielding  the  dehcate  pulp  from  in- 
coming dangers;  not  by  the  production  of  dentine  matrix,  but  by 
physiologically  creating  a  larger  or  more  concentrated  area  of  trophic 
influence  or  control — if  one  may  so  speak — on  the  surface  of  that 
organ,  whereby  its  vitality  may  be  retained  until  the  latest  possible 


*7 


Fig.  165. — Acute  inflammation  of  the  pulp  in  situ.  Prepared  as  in  the  pre- 
ceding. Magnified  130  times,  d.  Dentine;  o.  Inflamed  odontoblasts;  p.  In- 
flamed pulp  tissue;  b.  Small  vein  with  axial  current  of  blood  corpuscles  and,  at 
the  sides,  emargination  of  the  leucocytes. 

moment;  or  it  may  be  that  the  odontoblasts  have  merely  undergone 
mitosis.     This  is  probably  the  correct  view  to  hold. 

True  formations  of  compact  bone  are  most  rarely  found  in  the 
tooth-pulp;  several  cases,  however,  have  been  recorded  (see  pp.  68, 
69),  but  calcareous  deposits  are  exceedingly  common. 

Compact  osseous  tissue  consists  of  Haversian  canals,  concentric 
and  intermediary  lamellae,  lacunae,  and  canaliculi,  with  blood-vessels, 
osteoblasts,  connective  tissue,  branched  bone  corpuscles,  and  minute 
lymphatic   systems.     (See   Chap.  VI,  Vol.  I.)     And  if  these  com- 


DISEASES    OF   THE   DENTAL   PULP  151 

ponent  parts  are  non-existent,  it  is  a  mistake  to  pronounce  the  new 
formation  bone. 

(2)  Turning,  in  the  second  place,  to  cases  in  which  the  dentine 
is  well  developed  and  free  from  irregularities,  the  subjective  pain 
symptoms  do  not,  as  a  rule,  appear  until  there  is  almost  penetration 
into  the  pulp  chamber,  no  matter  how  rapidly  the  carious  encroach- 
ments may  take  place.  But  the  pulp  exhibits  similar  microscopical 
characteristics  to  those  already  detailed,  the  most  obvious  being 
cell-proliferation  and  odontoblast  multiplication  with  isolated 
cylindrical  calcoglobulin  formations  in  the  neighbourhood  of  the 
vessels.  Regional  hyperaemia  is  often  present — that  is,  the  capil- 
laries, arteries,  and  veins  are  rather  larger,  have  thinner  walls,  and 
are  more  tortuous  than  normal. 

Acute  Inflammation 

Definition. — This  is  one  of  the  terminations  of  hyperaemia,  and 
also  one  of  the  results  of  dental  caries.  It  is  one  of  the  commonest 
affections  of  the  pulp,  because  of  the  anatomical  peculiarities  of 
the  parts,  and  of  the  prevalency  and  numbers  of  its  causes.  Syno- 
nym: Pulpitis,  a  hybrid  term. 

Etiology. — (i)  Caries;  (ii)  The  incautious  use  of  drugs;  (iii) 
Fillings  of  an  irritant  or  thermal  conducting  nature;  (iv)  Trau- 
matism; (v)  As  an  extension  of  inflammation  from  the  alveolo- 
dental  periosteum.  The  latter  is  septic  in  origin  and  occurs  in  teeth 
whose  roots  are  more  or  less  incomplete,  and  whose  apical  foramina 
are  still  very  patent. 

Terminations. — Resolution,  organisation,  suppuration,  or 
gangrene. 

Signs  and  Symptoms. — The  Galenic  signs  of  acute  inflammation 
are  manifested  in  the  pulp  as  elsewhere,  but  vary  greatly  in  inten- 
sity. Thus  pain  (dolor)  is  the  greatest,  whilst  swelling  and  heat 
(tumor  et  calor)  owing  to  its  circumscribed  environment  are  the  least. 
The  pulp  macroscopically  becomes  very  red  (rubor).  The  first  is 
due  to  pressure  upon  the  nerve  bundles  and  the  great  tension  pro- 
duced by  the  hyperaemia;  and  the  others  are  due  to  hyperaemia, 
leucocytic  emigration,  serous  exudation,  proliferation  of  "fixed" 
tissue  elements,  and  the  relatively  large  amount  of  blood  in  the 
parts. 

GENERAL    HISTOLOGY 

Inflammation  is  the  complete  local  reaction  of  the  tissues  to  in- 
juries and  lesions  of  various  kinds. 


152  THE    DENTAL    TISSUES 

"In  recent  years  it  has  become  more  and  more  evident  that  the 
only  theory  which  allows  the  full  meaning  of  inflammation  to  be 
grasped,  is  the  broad  biological  conception  which  recognises  in  in- 
flammation an  adaptive  protective,  and  reparative  tendency  com- 
mon to  the  reactions  to  injury  among  all  animals."  (Hektoen  and 
Riesman.     "A  Text-book  of  Pathology,"  1901.) 

To  Cohnheim^  and  Metchinkoff-  belong  the  credit  for  a  great 
deal  of  the  early  and  late  knowledge  of  this  subject.  "  Inflammation 
brings  into  operation  a  number  of  factors  to  counteract  harmful 
agents,  protect  the  organism  at  large,  and  effect  healing.  The 
common  mode  of  origin,  the  similarity  of  the  changes  (though 
combined  in  different  proportions)  and  the  evident  tendency  of 
the  inflammatory  processes  to  protect  and  repair,  justify  fully 
the  teaching  that  inflammation  is  essentially  an  adaptive,  protective, 
and  reparative  process,  a  means  of  self-preservation.  Yet  it  must 
not  be  forgotten  that  the  mechanism  of  defence  and  preservation 
is  far  from  perfect;  the  exudate  may  possess  but  little  bactericidal 
power;  the  phagocytes  may  be  powerless,  or  the  bacteria  may 
multiply  freely  within  them;  extensive  destruction  of  tissue  may 
occur  before  the  virulence  of  the  bacteria  is  neutralised;  the  "fixed" 
cells  may  form  imperfect  material  for  repair  or  multiply  in  excess 
.    .    .      The  inflammatory  reaction   does  not  respect  the  relative 

importance  of  the  tissues Hence,  inflammation,  though 

biologically  an  adaptive  and  preservative  process,  may  appear 
harmful,  requiring  the  intervention  of  medical  art.  Taking  all 
things  into  consideration,  we  may  conclude  that  inflammation  is 
a  reaction  to  local  injuries,  calling  forth  protective  and  reparative 
measures;  but  that  it  is  an  imperfect  pathological  adaptation,  often 
leading  to  consequences  that  are  dangerous  per  se  and  defeat  its 
purpose."     (Hektoen  and  Riesman.     Op.  cit.) 

As  this  is  true  for  the  tissues  in  general,  so  does  it  equally  apply  to 
the  dental  pulp  in  particular. 

It  has  been  pointed  out  that  passive  or  venous  hypersemia  may 
soon  pass  into  a  condition  of  inflammation.  A  brief  sketch  of  the 
roles  that  are  severally  played  by  (a)  the  blood-vessels,  (b)  the 
colourless  blood  cells,  (c)  the  exudate,  (d)  the  "fixed"  cells,  and  (e) 
the  nervous  system  in  this  important  condition  must  now  be 
detailed. 

1  Cohnheim:  Archiv  filr  Pathol.  Anat.,  vol.  xv,  1867,  xxlv.,  1869. 

2  Metchinkoff :  L'Immunite  dans  les  Maladies  Infectieuses,  1904.  Pathologic 
Comparative  de  I'Inflammation,  1891. 


DISEASES    OF    THE    DENTAL   PULP  1 53 

(a)  The  Blood-vessels. — It  is  believed  that  the  vessel  walls  are 
structurally  altered  during  the  course  of  inflammation  to  allow  of 
and  facilitate  the  emigration  of  the  blood  cells  and  plasma.  Their 
endothehal  cells  are  contractile  (Klebs)  and,  according  to  Metch- 
inkoff,  mobile  and  phagocytic,  and  by  frequently  enlarging,  cause 
an  increased  resistance  to  the  vascular  stream. 

{b)  The  colourless  cells  play  a  fundamental  part  in  the  process, 
by  passing  into  the  perivascular  tissues,  as  first  pointed  out  by  Du- 
trocht  in  1828.  Cohnheim  laid  great  stress  on  this  phenomenon. 
Detaching  themselves  from  the  marginal  current,  which  they  nor- 
mally occupy  on  account  of  their  low  specific  gravity,  they  become 
attached  to  the  endothehal  fining  of  the  wafis;  and,  as  a  result  of  a 
localised  positive  chemio-taxis  produced  by  the  diffusible  products 
of  bacteria,  drugs,  etc.,  emanating  from  the  seat  of  the  lesion,  pass 
through  the  intercellular  cementing  substance.  Leucocytic  emi- 
gration is  a  compficated  process,  and  varies  with  the  nature  of  the 
cefis  actively  engaged  in  it;  thus  there  may  be  more  eosinophiles 
than  small  mononuclear  leucocytes,  etc.  The  emigration  is 
favoured  by  the  dilatation  of  the  blood-vessels  and  the  contractiHty 
and  mobility  of  the  endothehal  cells;  and  is  determined  by  positive 
chemio-taxis  by  which  the  leucocytes  advance  toward  the  foci  of 
greatest  attraction. 

The  erythrocytes  follow  the  white  cefis  at  greater  or  shorter  in- 
tervals of  time. 

Phagocytosis  is  the  action  of  certain  leucocytes  and  wandering 
cells — with  endothelial  and  "fixed"  connective  tissue  cefis  to  a  lim- 
ited extent — which  occurs  in  the  presence  of  pathogenic  bacteria 
and  other  particles  of  matter.  A  kind  of  intra-cellular  digestion 
takes  place,  alexins — protective  bactericidal  bodies — being  formed, 
either  by  a  process  of  secretion,  or  as  Hardy  befieves,  excretion, 
and  the  adventitious  material  being  destroyed.  The  function  is 
carried  out  by  the  neutrophile  cefis,  and  the  polymorphonuclear 
leucocytes,  and  also  perhaps  the  mononuclear  leucocytes.  Negative 
chemio-taxis — the  antithesis  of  positive  chemio-taxis — means  the 
insensibility  of  phagocytes  to  and  their  actual  repulsion  from  the 
toxins  present  in  any  particular  part. 

The  inflammatory  exudates  possess  also  bactericidal  properties, 
as  shown  by  the  experiments  of  Buchner,  Nissen  and  others,  and 
assist  the  phagocytes  in  their  beneficial  operations.  Afi  leucocytes 
are   not  phagocytes — eosinophiles  are   not;   they  possibly  possess 


154  THE    DENTAL    TISSUES 

excretory  functions  and  may  diminish  the  vitality  of  the 
micro-organisms. 

(c)  The  inflammatory  exudates  contain  more  proteids  than 
physiological  lymph,  also  fibrin,  fibrinoplastin,  etc.,  and  certain 
digestive  ferments  and  peptones.  The  quantity  is  very  insignificant 
in  the  pulp  tissue;  the  serous  and  sero-fibrinous  and  fibrous  exudates 
are  small  in  amount  and  poor  in  quality;  but  the  haemorrhagic 
exudate,  originated  by  the  intensity  of  the  primary  lesion  and  due 
to  an  enormous  emigration  of  the  erythrocytes  is  very  marked. 
After  traumatic  exposure  of  the  pulp,  during  excavation  of  a  deep 
carious  cavity,  for  instance,  where  a  thin  layer  of  dentine  remains  in 
the  floor,  there  is  often  a  large  flow  of  arterial  and  capillary  blood, 
signifying  extensive  changes  in,  and  injuries  to  the  vessel  walls  and 
also  a  great  quantity  of  hsemorrhagic  exudate. 

{d)  "Fixed^'  Tissue  Elements. — Retrogressive  and  progressive 
changes  may  go  on  side  by  side,  but  the  former  are  more  pronounced 
in  the  earlier  stages  of  acute  inflammation.  Inflammation  follows 
injuries  that  produce  lesions  not  sufficiently  great  to  induce  com- 
plete necrosis  and  death  of  the  part.  No  inflammation  of  the  pulp 
is  set  up  by  cocaine  pressure  anaesthesia:  it  is  anaesthetized  merely. 
But  in  carious  encroachments  which  give  rise  to  an  acute  inflam- 
mation the  pulp  cells  become  greatly  damaged  and  undergo 
extensive  retrogressive  changes.  Necrosis  and  necrobiosis  of 
the  "fixed"  cells  and  leucocytes  occur.  The  odontoblasts  at  the 
site  nearest  to  the  lesion  become  fatty  and  degenerate;  while  further 
away  they  become  "sheathed,"  and  show  signs  of  proliferation. 
This  is  probably  an  attempt  on  their  part  to  heal  the  injury  or  pre- 
vent further  damage  from  taking  place,  by  warning  the  pulp,  so 
to  speak,  of  the  oncoming  dangers;  and  perhaps  even  to  stimulate 
the  dentine-depositing  cells  about  them  to  functionate  and  pro- 
duce adventitious  dentine.  These  phenomena  will  be  presently 
further  alluded  to. 

(g)  The  sympathetic  nervous  system  exercises  a  certain  amount 
of  influence  in  inflammation.  Hyperaemia  and  exudation  are  in- 
terfered with  by  the  uncontrolled  action  of  the  vaso-constrictors, 
the  toxins  are  not  removed,  and  repair  of  the  injury  cannot  be  prO' 
ceeded  with.  If,  on  the  other  hand,  the  vaso-dilators  exceed  their 
functions,  congestion  takes  place  enormously  or  a  strangulation 
of  the  vessels  of  the  radicular  regions  chiefly  soon  leads 
to  moist  gangrene  of  the  entire  organ. 


DISEASES    OF    THE    DENTAL    PULP 


155 


SPECIAL   HISTOLOGY 

Acute  inflammation  will  be  considered  under  two  aspects: — 
(.4)  When  caries  has  not  penetrated  into  the  cavity,  and   (B) 
when  it  has  penetrated. 

A 
Conditions  Associated  ivith  Non-penetrating  Caries 

The  odontoblasts,  in  the  cervical  regions,  are  enormously  mul- 
tiplied in  point  of  numbers  and  layers.  The  cells  themselves 
are  not  enlarged,  but  possess  prominent  oval  nuclei  which  are  much 
flattened  laterally.     Interposed  here  and  there  are  small,  hitherto 


Fig.  166. — Acute  inflammation  of  the  pulp,  with  masses  of  calcoglobulin  in 
situ.  Prepared  as  in  Fig.  163.  d.  Dentine;  p.  Pulp  tissue;  b.  Enlarged  capillary ; 
c.   Calcoglobular  mass. 

undescribed  translucent  globules,  structureless  and  non-laminated, 
but  similar  in  other  respects  to  tiny  calcospherite  spherules  (see 
Fig.  166).  These  are  seen  at  the  dentine  border  between  the  cells, 
and  sometimes  in  Weil's  layer.  At  the  junction  of  the  carious 
region  with  the  primary  or  first-formed  dentine  the  latest  deposited 
dentine  has,  at  its  periphery,  the  globular  appearances  observed 
during  developmental  periods.     It  takes  aniline  dyes  more  deeply 


156 


THE   DENTAL   TISSUES 


Fig.  167. — An  early  stage  of  chronic  (?)  inflammation  of  the  pulp.  Prepared  as 
in  Fig.  163.  Magnified  30  times,  d.  Dentine;  p.  Pulp;  b.  Enlarged  blood- 
vessel; o.  Odontoblasts  gathered  into  sheaves. 


DISEASES    OF    THE    DENTAL    PULP  1 57 

than  the  normal  dentine,  from  which  it  is  highly  differentiated. 
This  new  tissue  may  be  called  "adventitious"  dentine — a  term 
which  includes  several  varieties  previously  noted.  At  the  places 
where  the  carious  tubules  open  into  this  freshly  deposited  layer, 
the  odontoblasts  are  considerably  shrunken,  and  pressed  inwards 
towards  the  pulp.  They  are  disposed  in  one,  or  at  most,  two  layers, 
and  their  peripheral  poles  (dentinal  fibrils)  are  greatly  enlarged  and 
swollen.  The  layer  of  Weil,  of  adult  pulps,  is  most  marked  here. 
Micrococci  and  bacilH  infect  the  newly  formed  tubes,  and  in  some 
places  expand  them.  And  where  tubular  expansion  has  been 
effected,  there  the  odontoblasts  are  absent,  their  places  being  oc- 
cupied by  a  homogeneous  mass  of  broken-down  cells,  with  a  few 
necrosed  or  necrobiotic  nuclei  scattered  about.  Active  hyperaemia 
is  distinguished  by  enlargement  and  tortuosity  of  the  capillaries 
and  arterioles,  their  engorgement  with  blood,  and  emigration  of 
leucocytes  (see  Figs.  163  and  165). 

As  the  thin  sheet  of  adventitious  dentine  gradually  widens  out, 
the  odontoblasts  become  elongated,  remaining  all  the  time  in  one 
layer,  their  fibrils,  each  with  its  individual  enveloping  tube,  being 
of  normal  size,  and  stretching  across  the  new  dentine  at  fairly 
regular  intervals.  The  cells  themselves  are  sometimes  gathered 
into  sheaves — a  condition  frequently  noticed  in  degenerative 
changes  (see  Fig.  167).  With  the  widening  of  the  sheet  of  dentine, 
they  become  smaller  and  shorter,  and  diminish  rapidly  in  number, 
until  they  disappear  altogether. 

Meanwhile  the  adventitious  dentine  presents  the  well-known 
appearance  of  areolation  almost  identical  with  that  of  the  inter- 
globular spaces.  This  areolar  adventitious  dentine  has  been  de- 
scribed on  p.  72.  The  structure  of  the  pulp  itself  at  this  place  is 
of  the  homogeneous  character  already  noted.  Thus  the  vessel 
walls  are  changed,  the  endothelial  cells  being  enlarged  and  projecting 
into  the  lumina  of  the  capillaries,  and  undergoing  mitosis.  The 
active  movements  of  the  emigrated  leucocytes,  which  have  already 
passed  through  the  intercellular  cement  substance  of  the  vessel 
walls,  are  directed  to  certain  areas  in  the  tissue  through  the  influence 
of  positive  chemio-taxis  set  up  by  the  diffusible  products  of  the 
bacteria  (bacteri-proteids)  in  the  tissues,  and  of  other  substances. 
The  serous  or  sero-fibrinous  exudation  is  necessarily  slight;  and  the 
fixed  connective  tissue  cells  of  the  pulp,  having  undergone  cytogeny, 
suffer  from  retrogressive  changes,  and,  becoming  necrotic  or  necro- 
biotic, show  signs  of  cloudy  sweUing,  disintegration  and  death. 


158 


THE   DENTAL  TISSUES 


The  dentine  which  fills  the  cornua  of  the  pulp  exhibits  irregular 
formations,  as  if  deposition  had  taken  place  in  a  hurried  manner. 
Not  only  are  nucleated  cells  with  long  processes  imbedded  in  the 
hard  mass,  but  large  lacunal  spaces  are  frequent,  each  containing 
micrococci  which  have  entered  via  the  tubules  of  the  primary  dentine. 
In  some  instances  this  cellular  dentine  somewhat  resembles  the 
structure  of  sponge. 

A  bacteriological  survey  of  the  same  specimens  of  hyperaemia 
and  early  stages  of  the  lesions  which  Rothmann^  has  designated 


Fig.  i68. — Acute  inflammation  of  the  pulp.  Stained  with  Ehrlich's  acid 
hasmatoxylene  and  eosin.  Shows  the  inflammatory  products  attracted  to  a 
focus  of  inflammation,  p.  Leucocytes  and  proHferated  connective  tissue  cells; 
i.F.   Inflammatory  focus. 


"Partial  acute  pulpitis,"  and  WedP  "Pulpitis  acuta  partialis/' 
furnishes  one  with  some  valuable  particulars  as  to  the  probable 
distribution  of  the  micro-organisms  in  the  pulp  and  surrounding 
tissue.  Miller^  has  isolated,  cultivated,  and  named  the  most 
important  of  the  cocci  and  bacilli;  here  is  an  opportunity  of  describ- 
ing the  probable  routes  of  their  invasion  of  the  pulp  itself. 

The    micro-organisms,    after    their    introduction   into    the   pulp 

1  "Patho-Histologie  der  Zahnpulpa  und  "Wurzelhart,"  1889. 

2  "Atlas  zur  Pathologie  der  Zahne,"  pp.  68,  69,  1893. 
^  "Micro-organisms  of  the  Human  Alouth,"  1889. 


DISEASES    OF    THE    DENTAL   PULP  1 59 

cavity,  are  believed  to  make  their  way  in  chains,  groups,  or  masses 
to  the  spaces  between  the  odontoblast  layer,  the  dento-genetic  and 
ordinary  pulp  cells  on  the  one  side,  and  the  border  of  dentine  on  the 
other;  and  also  to  the  interpolar  (interfibrillar)  spaces,  and  the 
intercellular  intervals.  Thence  they  travel  apparently  to  the  basal 
layer  of  Weil,  although  here  they  are  not  congregated  in  such  large 
or  such  numerous  masses.  Whatever  their  point  of  entrance,  they 
soon  pass  to  some  considerable  distance  along  the  Hne  of  junction  of 
the  hard  and  soft  tissues. 

Further,  they  are  found  in  the  substance  of  the  pulp  proper, 
chiefly  arranged  along  the  walls  of  the  blood-vessels,  in  their  inte- 
riors (when  empty),  and  in  the  perivascular  tissues.  Infection  of  the 
nerve  fasciculi  most  probably  does  not  take  place.  The  micrococci 
predominate  largely  over  the  rod-shaped  organisms.  The  central 
and  peripheral  portions  of  the  adventitious  dentine  are  crammed  with 
micro-organisms,  but  when  the  odontoblast  fibrils  with  their  sheaths 
cross  the  areolations  of  this  new  deposit,  no  bacteria  can  be  found. 

From  these  investigations,  therefore,  it  will  be  seen  that,  as  a 
result,  one  is  unable  to  coincide  with  Arkovy's  theory  of  the  phago- 
cytic function  of  the  odontoblasts.^  They  certainly  possess  a  granu- 
lar appearance,  but  a  search  for  any  micro-organisms  which  have  be- 
come incorporated  in  the  substance  of  their  cytoplasm  or  nuclei  is 
attended  with  negative  results. 

If  the  course  of  the  disease  is  progressive,  inflammatory  foci 
appear.  These  consist  of  proliferated  connected  tissue  cells  (macro- 
phages), pulp  cells,  and  lymphocytes  or  polymorphonuclear  leu- 
cocytes which  have  escaped  from  the  numerous  enlarged  capillaries, 
all  having  been  attracted  together  by  positive  chemio-taxis.  The 
foci  are  very  pronounced,  commence  at  first  in  one  or  both  of  the 
cornua  of  the  pulp  opposite  the  carious  dentine,  and,  as  a  rule, 
ultimately  suppurate  and  form  locaHsed  abscesses  (Figs.  169  and 
170).  Rapid  destruction  of  the  pulp  ensues,  and  the  undermined 
dentine  finally  gives  way  in  the  majority  of  cases. 

Sometimes  a  certain  amount  of  fibrification  of  the  cells  lying  in 
the  immediate  vicinity  of  the  abscess  occurs,  and  what  might  be 
termed  a  rudimentary  abscess  wall  is  developed.  One  is  led  to  beheve 
that  this  specialisation  and  grouping  of  spindle  cells  is  not  merely 
fortuitous,  but  a  dehberate  attempt  on  the  part  of  the  pulp  to  heal 
the  lesion.  The  condition  is  observed  in  cases  of  chronic  caries,  the 
adventitious  dentine  being  then  deposited  in  layers,  and  presenting 
'  See  Journal  of  Brit.  Denl.  Assoc,  vol.  xv.,  p.  602. 


i6o 


THE    DENTAL   TISSUES 


D   l-H     ° 
O  1^    O 


DISEASES    OF   THE   DENTAL   PULP 


l6l 


l62 


THE    DENTAL    TISSUES 


a  characteristic  fibrillar  structure.  On  the  border-hne  of  the  hard 
and  soft  parts,  the  connective  tissue  structure  of  the  dentine  matrix 
is  well  brought  out.  Islands  of  semi-calcified  material  in  the  body 
of  the  pulp  suggest  that  they  are  nothing  more  nor  less  than  calcified 
bundles  of  connective  tissue  fibres  mixed  with  cells;  the  process 
of  their  formation  being  analogous  to  that  of  intra-membranous 
ossification  of  bone  (see  Fig.  170). 

B 

Conditions  Associated  with  Penetrating  Caries 

The  exigencies  of  the  scope  of  this  book  afford  these  notes  oppor- 
tunity of  speaking  of  no  more  than  two  phases  of  one  of  the  com- 


FiG.  171. — Inflammation  of  the  pulp.  The  odontoblasts  have  been  torn 
away  from  the  surface  of  the  dentine,  to  show  the  presence  there  of  the  proliferated 
connective  tissue  cells,  leucocytes,  and  other  products  of  the  inflammation. 
Prepared  by  the  Author's  process.  Stained  with  Ehrlich's  acid  hasmatoxylene. 
Magnified  i8o  times,  d  Dentine;  p.  Pulp  tissue;  O.  Odontoblasts;  i.  Inflam- 
matorv  cells,  etc. 


monest  conditions  found  in  the  mouth,  viz.,  idiopathic  exposure 
of  the  pulp. 

In  sagittal  sections  of  teeth  affected  by  acute  caries,  which  has 
terminated  in  acute  inflammation  and  partial  suppuration  of  the 
pulp,   it  is   obvious   that   the   cells  appear  degenerate  altogether. 


DISEASES    OF    THE    DENTAL    PULP 


163 


Connective  tissue  cells  are  broken  down,  the  pulp  cells  have  become 
changed  into  indifferent  cells  with  large  square  nuclei,  and  escaped 
leucocytes  crowd  the  tissues.  Even  the  odontoblasts  themselves  at 
the  cervical  region  are  metamorphosed  into  short  cells  with  rounded 
nuclei,  and  at  the  coronal  part  are  opaque,  and  seem  to  have  under- 
gone fatty  or  mucoid  degeneration  (Fig.  172). 

Finally,  at  the  periphery  of  the  pulp  the  small  globular  deposits, 
already  mentioned,  are  found.  The  nerve  bundles  have  lost  their 
definite  structure,  and  though  retained  in  position  are  evidently  less 


Fig.  172. — Acute  inflammation  of  the  pulp.  Prepared  and  stained  as  in  the 
preceding  figure.  Magnified  80  times,  d.  Dentine;  p.  Pulp  tissue  crowded 
with  inflammatory  products;  O.  Odontoblasts. 


translucent  and  more  disorganised.  There  are  no  clear  evidences 
of  fatty  degeneration  in  the  sections  under  notice,  although  WedF 
describes  this  as  existing  in  his  sections  of  acute  purulent  pulpitis. 
The  tissues  are  greatly  condensed  at  the  margins  of  the  abscess 
cavity,  the  cells  being  short  and  fusiform,  and  interlacing  closely 
with  each  other.  The  blood-vessels  are  hyperasmic,  and  micrococci 
and  bacilli  are  abundantly  distributed  throughout  the  tissue. 

The  last  condition  which  will  be  here  considered  is  that  of  a  phase 
of  acute  partial  suppurative  inflammation  of  the  pulp,  in  which 

'  Op.  cil.,  p.  71. 


164  THE    DENTAL    TISSUES 

that  organ  has  been  subjected  to  the  devitaHsing  action  of  arsenious 
acid  for  a  period  of  not  less  than  twelve  hours. 

In  addition  to  appearances  which  denote  the  intensity  of  the 
inflammation — hyperaemia,  marked  cellular  infiltration,  suppuration 
and  other  changes  common  to  acute  inflammations  in  soft  tissues — 
a  prominent  feature  is  a  large  special  form  of  dentinal  deposit  which 
is  situated  at  the  base  of  the  carious  opening  into  the  pulp  chamber. 
This  is  cellular  and  hyaline  adventitious  dentine  previously  described 
on  pp.  72  and  74. 

This  particular  form  of  cellular  or  hyaUne  adventitious  dentine 
does  not  occur  solely  in  acute  inflammation  of  the  pulp,  it  is  also 
seen  in  chronic  inflammation  with  hyperplasia  ("polypus")  near 
the  lower  portion  of  the  pulp  cavity.  In  this  case  it  may  be  accom- 
panied by  new  dentine  which  has  a  pronounced  laminar  structure. 

In  conclusion,  a  study  of  the  patho-histology  of  these  lesions  leads 
one  to  the  following  deductions : — - 

(i)  That  nearly  every  degree  of  dentinal  change  is  attended 
with  hyperaemia,  and  cell  proliferation  in  the  pulp  tissues,  and  gener- 
ally speaking,  the  formation  of  adventitious  dentine: 

(2)  That  the  latter  may  have  its  origin  as  a  conversion  or  secretion 
of  the  dento-genetic  cells,  producing  on  the  one  hand  the  areolar  or 
laminar  or  hyaline  varieties,  when  the  formative  cells  alone  happen 
to  be  concerned;  on  the  other,  the  fibrillar  or  cellular  forms  when 
odontoblasts  or  connective  tissue  cells  are  by  chance  incorporated 
in  the  deposit: 

(3)  That  the  new  dentines,  by  a  system  of  extension  from  the 
affected  areas,  may  be  just  as  much  subjected  to  the  peptonising 
action  of  micro-organisms  as  the  primary  dentine  of  the  tooth. 

Chronic  Inflammation 

This  is  sometimes  one  of  the  sequelae  of  acute  inflammation. 
The  pathological  processes  are  essentially  the  same.  The  changes, 
however,  are  continuous,  thus:  The  dilated  vessels  remain  in  a 
condition  of  dilatation  and  lose  their  tone,  leucocytes  continue  their 
work  of  emigration  through  the  vessel  walls,  and  the  original  tissue 
cells  still  further  proliferate. 

Etiology. — The  causes  are  similar  to  those  of  the  acute  conditions; 
but  certain  general  systemic  diseases  such  as  rheumatism,  gout, 
hydrargyrism,  etc.,  are  believed  to  be  powerful,  predisposing,  and, 
in  some  cases,  exciting  causes. 


DISEASES    OF    THE    DENTAL   PULP  165 


HISTOLOGY 


It  is  nearly  always  associated  with  the  formation  of  large  masses 
of  calco-globulin  nodules  in  the  pulp,  and  may  go  on  until  the  whole 
of  the  pulp  tissue  becomes  converted  into  a  hard  calcareous  mass. 

When  there  is  exposure  of  the  pulp,  these  deposits  of  calco- 
globuHn  are  always  seen  in  the  region  of  the  inflamed  area.  They 
are  irregular  in  shape,  and  often  attain  a  large  size,  and  fill  up  the 
pulp  tissue.  Sometimes  these  dentine  masses  extend  throughout 
the  pulp  hke  long  rods  running  parallel  with  the  walls  of  the  pulp 
chamber.  The  pulp,  when  removed  from  its  cavity,  is  found  to  be 
stiffened  and  hard  from  the  presence  of  these  calcified  rods.  They 
are  seen  in  the  immediate  neighbourhood  of  the  blood-vessels  and 
nerve  bundles. 

When  stained,  for  microscopical  purposes,  they  behave  like  the 
dentogenetic  zone  in  developing  teeth— that  is  they  take  fuchsine, 
hsmatoxylene,  carmine,  and  other  stains  very  intensely. 

If  there  is  an  extensive  exposure  of  the  pulp,  the  tissue  often 
undergoes  productive  inflammation,  and  becomes  hyperplasic,  and 
the  condition  known  as  polypus  is  found. 

Hyperplasia  of  the  pulp  is  a  chronic  productive  inflammation, 
in  which  the  redundant  material  formed  is  extruded  through  the 
opening  at  the  base  of  the  carious  cavity.  At  first  small,  it  slowly 
increases  in  size,  until  ultimately  a  large  soft  fungating  mass  fills 
up  the  cavity,  and  sometimes  overhangs  its  edge.  It  must  be 
diagnosed  from  hypertrophy  of  the  gum,  the  two  points  of  difference 
being  usually  easily  determined. 

Hyperplasia  of  the  pulp  is  probably  caused  by  the  irritation  of 
sharp  dentinal  margins  of  the  pulp  cavity,  which  become  slowly 
absorbed  as  the  condition  advances. 

The  patho-histology  is  interesting.  The  mass  consists  briefly  of  (i) 
a  superficial  epithelial  layer,  (ii)  a  stroma  or  frame-work  of  strong 
fibrous  tissue,  (iii)  supporting  the  large  granulation-like  cells  and 
blood-vessels,  which  constitute  the  greatest  parts  of  the  growth. 

(i)  The  superficial  epithehal  covering  consists  of  a  stratified 
layer  or  layers  of  large  squamous  epithehal  cells.  The  occurrence  of 
squamous  epithelium  in  the  surface  of  a  tissue  which  does  not 
normally  contain  any  epithehal  cells  is  remarkable.  This  auto- 
plasty  was  formerly  believed  to  be  due  to  a  form  of  skin-grafting 
brought  about  by  the  transference  to  the  free  surface  of  the  exposed 
pulp  of  portions  of  epithelial  tissue  from  the  mucous  membra,ne  of 


i66 


THE    DENTAL    TISSUES 


the  cheek,  during  the  act  of  mastication.     The  truth  is  that  the 
surface  cells  of  a  portion  of  gum  which  overlaps  an  edge  of  carious 


Fig.  173.— a  large  fungating  hyperplasia  of  the  pulp  overhanging  the  edge  of 
a  carious  cavity.  Stained  with  hajmatoxylene  and  cosine.  Magnified  230 
times.  D.  Normal  dentine;  e.  Edge  of  carious  cavity,  c.  Cementum;  p.  Pulp 
tissue;  e.a.   Epithelial-like  areas  in  pulp. 

dentine  rapidly  proliferate  as  a  result  of  the  mechanical  irritation, 
and  spread  over  the  exposed  portion  of  the  pulp  to  which  they 
finallv  become  ftrmlv  adherent. 


DISEASES    OF    THE    DENTAL    PULP 


167 


The  periphery  of  the  growth  may  present  one  or  two  different 
structures,  (i)  It  generally  consists  of  very  flattened  non-nucleated 
cornified  squamous  epithelial  cells,  with  little  intercellular  cement 
substance.  (2)  The  periphery  may  closely  copy  the  ordinary 
epithelial  characteristics  of  the  mucous  membrane  of  the  mouth 
.and  gums,  that  is  to  say,  its  sub-mucous  surface,  is  thrown  into 
innumerable  folds  or  papillse. 

In  the  first  instance  several  thin  layers  of  epithelial  cells,  arranged 
as  strata,  sometimes  may  be  found.     The  outer  layers  are  composed 


Fig.  174. — Chronic  inflammation  of  the  pulp,  with  hyperplasia  of  that  tissue 
(so-called  "polypus").  Prepared  as  in  the  preceding  figure.  Magnified  250 
times.  B.  Blood-vessel  crowded  with  corpuscles;  c.  Nuclei  of  the  inflammatori^ 
cells. 

of  fiat  cells,  the  inner  of  ovoid  cells,  generally  two  or  three  rows. 
Each  cell  is  granular.  Finally,  there  appears  the  stratum  Malpighii, 
where  the  cells  are  smaller  and  columnar  in  shape  with  oval  nuclei. 
These  rest  on  the  papillae,  a  sort  of  basement  membrane  dividing 
them  from  the  general  sub-mucous  tissues  beneath.  The  papilla 
found  in  the  second  instance  are  conical  elevations  projecting 
into  the  layer  of  the  rete  Malpighii.  If  they  are  undivided  they 
are  known  as  Simple;  if  they  are  beset  with  smaller  papillae  they 
are  called  Compound.  They  consist  of  compact  fibrous  tissue. 
The  rest  of  the  "polypus"  proper  consists  of  a  fibrous  stroma, 


1 68  '  THE   DENTAL   TISSUES 

in  which  the  fibrous  tissue  is  very  pronounced,  firm,  and  interlacing 
in  all  directions.  In  the  meshes  of  this  reticulum  are  found  large 
granulation  cells,  some  round,  some  square,  and  each  having  a 
large  nucleus  (see  Fig.  174). 

The  capillaries  terminate  at  the  periphery,  and  run  amongst 
the  meshes  of  the  stroma.  At  its  attachment  to  the  pulp  cavity, 
the  fibrous  tissue  is  arranged  in  strong  bands  which  stain  a  deep 
yellow  colour  with  picric  acid.  The  blood-vessels  in  this  portion  are 
scanty,  but  larger  than  those  seen  at  the  periphery. 

Here  also  rounded  masses  of  laminar  adventitious  dentine  are 
found.  They  have  a  laminated  nature,  one  or  two  small  cells 
occasionally  occupying  the  interior  of  the  pulp  nodule. 

In  the  pages  of  VOdontologie  of  September  15th,  1902,  Pont 
describes  an  extremely  curious  neoplasm  of  the  pulp  which  is  almost 
unique  in  the  annals  of  Dental  Pathology. 

Under  the  title  of  "Note  sur  un  cas  de  Tumeur  de  la  Pulpe 
dentaire  sans  carie  de  la  dent,"  an  account  is  given  of  this  anomaly, 
occurring  in  the  second  maxillary  right  premolar  of  a  man  of  35 
years.  He  complained  of  pain.  An  enamel  chisel  removed  the 
occlusal  surface  of  the  tooth  which  was  perfectly  sound,  and  revealed 
a  "soft,  deep  red,  easily  torn,  but  not  painful  growth  of  the  pulp, 
which  had  produced  absorption  of  the  cavity  walls."  It  was 
extirpated  easily,  the  operation  being  unattended  by  much 
haemorrhage. 

A  histological  examination  having  been  made  by  Dr.  Charvet, 
of  the  Faculty  of  Medicine,  of  Lyons,  this  gentleman  reports  that 
it  was  not  a  tumour  properly  so-called,  but  probably  a  simple  inflam- 
matory condition  of  the  pulp.     He  wrote  as  follows: — 

"La  piece  a  examiner,  n'a  nullement  le  caractere  d'une  tumeur. 
Sur  les  coupes  colorees  au  picro-carmin,  on  trouve  des  traces  de 
travees  sclereuses,  et  dans  tous  les  points,  des  nappes  de  cellules 
inflammatoires;  ailleurs  enfin  des  hemorragies  interstitielles  plus 
ou  moins  etendues.  Nulle  part  il  n'y  a  de  masses  neoplasiques, 
ou  pouvant  y  faire  songer.  II  semble  s'agir  d'un  bourgeon  charnu 
inflammatoire  en  voie  d'organisation  sclereuse." 

Infective  Gangrene  of  the  Pulp 

These  chemical  and  biological  changes  proceed  very  rapidly.^  The 
first  stage  begins  as  a  post-mortem  change,  and  does  not  necessarily 
depend  upon  the  presence  of  Schizomycetes,  the  fact  being  that  both 
the  liquid  and   solid  constituents  of   the  pulp   immediately  after 


DISEASES    OF    THE    DENTAL   PULP  169 

its  death  are  capable  of  destroying  many  micro-organisms.  The 
changes  partake  more  of  the  nature  of  a  chemical  dissolution  than 
a  result  of  bacterial  infection,  and  are  dependent  upon  the  action 
of  the  unformed  soluble  ferments  found  in  the  pulp,  as  in  other  soft 
tissues.  These  soluble  ferments  or  enzymes  are  present  in  all 
living  tissues,  and  have  much  to  do  with  the  processes  of  metabolism. 
Thus  albumen  becomes  converted  by  these  enzymes  into  peptones 
and  hemi-albumens. 

Pathogenic  bacteria  are  capable  of  developing  in  the  soft  tissues 
and  bringing  about  the  changes  just  mentioned.  But  in  or- 
der tha.t  they  may  develop  sufi&ciently  to  produce  these  chemical 
changes  in  sufl&cient  amount  before  they  themselves  are  destroyed, 
there  must  be  some  local  focus  of  disease  or  area  of  chemical 
decomposition  present,  which  becomes  largely  invaded  by  pus- 
forming  micro-organisms. 

It  is  therefore  obvious,  that  if  the  balance  between  the  biological 
actions  of  the  invading  and  invaded  forces  is  maintained  in  equi- 
librium, simple  death  of  the  pulp  will  occur;  that  is,  its  general 
functions  will  cease,  its  physiological  resistance  to  disease  or  injury 
will  be  in  abeyance,  its  powers  of  undergoing  progressive  or  further 
retrogressive  metamorphoses  will  be  terminated,  and  it  will  remain, 
perhaps  for  many  years,  an  inert,  innocuous,  ineffectual  remnant 
of  its  former  self — pale  and  shrunken.  The  hard  parts  surrounding 
it  will,  at  the  same  time,  be  affected  by  the  loss  of  nutrition,  and 
the  enamel — probably  through  changes  in  the  subjacent  dentine, 
certainly  not  through  actual  alteration  of  its  own  structure  or 
chemical  composition — will  eventually  become  dark  and  lustreless. 
This  is  what  happens  in  the  case  of  a  tooth  which  has  been  " killed" 
by  a  blow  on  the  mouth. 

On  the  other  hand,  if  the  bacterial  infection  is  great  and  the 
albuminoid  bodies  thus  produced  are  voluminous  in  amount, 
toxic  enzymes  result.  These  are  very  active  poisons,  which  give 
rise  in  a  short  space  of  time  to  the  usual  chemical  products  of 
decomposition,  viz.,  carbonic  acid,  ammonia,  sulphuretted  hydrogen, 
and  certain  other  salts  and  water.  The  evolution  of  these  is  de- 
pendent upon  the  access  of  oxygen,  heat,  and  moisture. 

According  to  Buckley  {Trans.  Fourth  International  Dental 
Congress)  the  chemical  changes  of  putrefaction  are  those  of  hydra- 
tion, reduction,  and  oxidation.  In  the  first,  there  is  a  taking-up 
of  one  or  two  molecules  of  water,  in  the  second,  a  breaking-up 
and   decomposition   by  nascent  hydrogen,   and  in   the   third,   the 


lyo 


THE    DENTAL    TISSUES 


formation  of  carbonic  acid,  acetic,  nitrous,  nitric  and  similar  acids. 
Other  substances  manufactured  simultaneously,  in  varying  degrees, 
are  globulins,  toxic  enzymes,  peptones,  the  nitrogenous  amino-acids, 
leucin  and  tyrosin,  the  nitrogenous  amines,  methylamine,  pro- 
pylamine, etc.,  and  organic  and  fatty  acids  such  as  formic,  propionic, 
butyric,    valerianic,  palmitic  and  other  fatty  substances  and  also 


Fig.  175. — Vertical  section  of  infective  gangrene  of  the  pulp  removed  from 
its  containing  cavity.  Stained  by  Gram's  method.  Magnified  45  times. 
M.   Dense  masses  of  micro-organisms;  p.  Non-infected  pulp  tissue. 

putrescine  (C4H12N2),  and  the  isomers  cadaverine  and  neuridine 
(C5H14N2).  These  latter  become  quickly  converted  into  ammonia 
and  its  derivatives.  Thus  is  the  pulp  destroyed,  and  it  is  probable 
that  the  contents  of  the  dentinal  tubes  are  also  similarly  filled  with , 
the  end-products  of  decomposition. 

The  Pathogeny  of  Gangrene  of  the  Dental  Pulp 

A    frequent    termination    of    inflammation,    whether    traumatic 
in. origin  or  not,  is  gangrene,  or  mortification  of  the- pulp.     The 


DISEASES    OF    THE    DENTAL    PULP  171 

patho-histology  of  this  condition  has  been  studied  by  Dr.  Fritz 
Schenk,  of  the  Dental  Department  of  the  University  of  Vienna. 
An  interesting  article  from  his  pen  appears  in  the  Oesterreichisch- 
iingarische  Vierteljahrsschrij't  fiir  Zahnheilkunde,  for  March,  1902. 
The  following  are  some  of  his  important  observations. 

"At  the  apex  of  the  pulp  a  gangrenous  mass,  entirely  devoid  of  nor- 
mal tissue  elements,  is  found  in  the  earliest  stages  of  the  disease. 
A  hne  of  demarcation  cuts  this  off  from  the  healthy  portions  of  the 
organ,  and  contains  disintegrated  cells.  In  the  gangrenous  re- 
gion, as  has  just  been  stated,  no  cells  or  tissue  fibres  can  be  recog- 
nised, but  in  fresh  gangrenous  patches  fat  globules,  formed  by  a 
process  of  dissolution,  appear.  Micro-organisms  are  present  in 
this  situation,  according  to  Miller,  Arkovy,  and  Scheff.  This  con- 
dition corresponding  to  Rothmann's  "Pulpitis  gangrcenosa  chronica,''^ 
has  also  been  investigated  by  Witzel  and  Arkovy.  This  gan- 
grenous patch  is  surrounded  by  the  "line  of  demarcation."  The 
rounded  contours  of  nuclei  may  sometimes,  especially  if  a  solution 
of  eosine  be  used  as  a  staining  reagent,  be  noticed  at  the  borders  of 
this  patch.  Their  chemical  characters  may  be  altered,  and  indi- 
cate a  "transition  stage"  towards  final  dissolution.  In  the  neigh- 
bourhood of  the  non-gangrenous  portion  the  nuclei  decrease  in 
number;  and  this  together  with  the  passive  hypersemia  present  con- 
stitutes the  chief  signs  of  the  "line  of  demarcation." 

"In  the  remaining  tissue,  which  generally  borders  on  the 
gangrenous  portion,  and  is  in  course  of  inflammation,  there  is  one 
factor  to  be  especially  noted,  that  besides  migrated  red  blood- 
corpuscles  in  the  tissue,  the  vessels  appear  enlarged,  sometimes 
filled  with  coagulum.  The  appearance  may  be  seen,  both  in  longi- 
tudinal and  in  transverse  sections,  only  at  the  line  of  demarcation; 
nearer  to  the  gangrenous  portion  the  vessels  are  entirely  missing. 

"The  termination  of  an  inflammatory  process  in  the  pulp,  of  ten 
leads  to  gangrene,  which  does  not  cover  the  whole  or  major  portion 
of  the  pulp,  but  generally  only  includes  at  first  the  distal  parts. 
From  this  point  it  proceeds  towards  the  centre.  For  the  conclusion 
of  the  process  there  is  needed  a  longer  or  shorter  period;  therefore 
this  process  has  been  correctly  designated  Pulpitis  gangrenosa 
chronica. 

"Contemporaneously  with  this  course,  certain  phenomena  also 
occur  in  the  tissues,,  which  lead  to  the  destruction  of  the  pulp. 
These  processes  likewise  develop  comparatively  slowly. 

"In  the  first  place  one  process  regularly  occurs  in  such  pulps, 


172  THE    DENTAL    TISSUES 

the  importance  of  which  in  all  inflammatory  conditions  is  to  be 
specially  emphasised.  The  red  blood-corpuscles  secede  from  the 
coagulum  contained  in  the  enlarged  vessels.  One  observes  them 
lying  everywhere  freely  about  in  the  tissue.  Especially  remarkable 
is  this  at  the  line  of  demarcation,  where  the  colouring  can  be  seen 
macroscopically  or  with  the  magnifying  glass. 

''When  the  nutrition  of  the  protoplasm  of  the  cellular  tissue 
reaches  abnormal  conditions,  as  is  the  case  with  inflammation  of 
the  pulp,  it  may  easily  happen  that  in  the  protoplasm  there  super- 
venes coagulation  of  its  albuminoid  constituents,  which  may  be  of 
a  fibrino-plastic  nature.  This  view  in  regard  to  coagulation  (Alex. 
Schmidt)  is  here  adopted. 

"If  coagulation  of  the  protoplasm  has  once  occurred,  every 
function  within  it  which  is  necessary  for  the  preservation  of  the 
cellular  tissue  is  made  difflcult  in  performance,  and  the  cell  must 
therefore  go  through  a  retrogressive  metamorphosis,  which  finally 
leads  to  degeneration.  Furthermore,  the  general  law  is  also  of  effect, 
that  the  protoplasm  of  the  tissue  elements  has~a  certain  connection 
with  their  nuclear  formations. 

''Consequently,  both  morphological  constituents  of  the  cell — 
the  protoplasm  as  well  as  the  nucleus — are  indivisible  and  inde- 
pendent, in  order  to  manifest  the  vital  function  of  the  cell.  The 
nucleus  is  a  necessary  attribute  of  the  cell,  and  becomes  its  dominant 
constituent,  inasmuch  as  it  governs  its  growth.  It  undergoes 
mitosis,  and  influences  the  histological  differentiation.  The  nuclei 
produced  by  the  fission  resemble  the  mother-nucleus  (O.  Hertwig). 
Portions  of  protoplasm,  without  nuclei,  may  maintain  themselves 
for  a  time,  however,  without  multiplying. 

"Many  portions  of  protoplasm  are  incapable  of  fulfilling  their 
physiological  functions  as  soon  as  the  nucleus  has  disappeared  from 
them.  Leucocytes,  whose  protoplasm  possesses  qualities  of  life 
and  movement,  but  whose  nuclei  are  not  divisible,  die,  and  remain 
in  the  living  organism  as  pus  corpuscles. 

"The  protoplasm  which  is  fitted  to  absorb  material  from  the 
surroundings,  and  to  make  corresponding  use  of  it,  loses  all  the 
qualities  peculiar  to  it  through  the  coagulation  of  its  albuminoid 
bodies.  Through  this  coagulation  it  not  only  loses  the  power  to 
absorb  materials  and  to  convert  them,  but,  furthermore,  it  is  no 
longer  capable  of  phagocytic  functions. 

"  In  this  manner  it  can  be  easily  explained  that  in  chronic  gangrene 
of  the  pulp  the  first  impulse  for  its  origin  is  given  by  the  coagulation 


DISEASES    OF    THE    PENTAL    PULP  1 73 

of  the  protoplasm  of  the  cellular  tissue.     It  is  the  primary  affection, 
in  the  wake  of  which  follow  the  other  appearances  of  gangrene. 

"The  alterations  of  the  nuclei  appear  only  when  the  protoplasm 
has  lost  its  vitality  through  the  coagulation  of  the  albuminoid 
bodies.  By  this  means  the  relationship  between  the  nucleus  and 
the  protoplasm  entirely  ceases.  The  nuclei  become  smaller,  and 
gradually  lose  more  and  more  of  their  karyoplasm,  and  decrease 
in  size  until  they  have  shrunk  to  dot-shaped  remnants  of  the  chro- 
matic substance.  Finally  these  also  disappear,  and  one  only  sees 
circumscribed,  light,  uncoloured  portions  in  the  decayed  granular 
gangrenous  substance,  which  possibly  still  exist  as  the  last  remains 
of  the  former  nuclei.  It  is  true  that  the  cell  nuclei  exhibit  a  longer 
power  of  resistance  during  this  pathogenic  process  than  all  the  other 
tissue  constituents  of  the  pulp,  but  at  last  their  individual  recognis- 
able morphological  elements  disappear,  and  with  them  the  dignity 
of  being  able  to  act  in  the  regeneration  of  the  elements." 


CHAPTER  VI 

INJURIES  OF  THE  DENTAL  PULP 

Microscopical    Elements    tound    in:     (i)    Methods  of  healing  after 
wounds  of  the  pulp. 

GENERAL    CHARACTERISTICS 

Of  all  the  morbid  conditions  usually  associated  with  the  dental 
pulp  it  is  generally  conceded  that  those  reparative  processes  which 
occur  after  injury  or  during  the  course  of  a  disease  of  that  organ 
rank  first  in  interest  and  importance.  A  study  of  the  methods  by 
which  nature  attempts  to  repair  or  heal  a  lesion  is,  on  careful  con- 
sideration, one  of  the  most  fascinating  subjects  that  can  engage  the 
attention  of  the  pathologist.  If  this  is  so  generally,  in  the  great 
domain  of  general  surgery  and  pathology,  how  much  more  interest- 
ing to  dental  surgeons,  must  be  a  study  of  a  like  nature  when  con- 
nected with  that  most  delicate  organ  the  dental  pulp? 

It  is  not  at  all  surprising  that  this  is  a  structure  which  possesses 
great  recuperative  powers,  and  is  constantly  exercising  its  functions 
in  this  respect  by  undergoing  repair.  Very  seldom  indeed  can  a  le- 
sion of  the  soft  or  the  hard  parts  of  a  tooth  occur  without  a  corre- 
sponding attempt — more  or  less  successful — on  the  part  of  the  pulp 
to  ward  off  its  attacks.  For  in  the  exercise  of  its  highest  functions 
it  is  concerned  with  the  maintenance  of  the  vitality  of  the  tissues 
in  the  centre  of  which  it  is  placed.  Hence  any  invasion  by  disease, 
or  the  occurrence  of  an  accident  is  succeeded  by  a  resistance  which 
in  many  cases  is  highly  satisfactory,  and  the  tissues  are  not  devital- 
ised. Probably  nearly  every  dentinal  change  is  accompanied  by  some 
healing  process  of  the  pulp. 

The  restoration  to  a  normal  condition  of  pulp  lesions  partakes  of 
the  characteristics  both  of  those  of  the  soft  parts,  like  a  wound  of  the 
skin  or  other  vascular  tissue,  and  those  of  bones,  as  in  the  case  of 
fracture.  Instead  of  a  permanent  or  definitive  callus  being  formed 
in  the  pulp  cavity,  the  conditions  are  modified  through  the  anatom- 
ical peculiarities  of  the  part:  and,  as  a  result,  the  various  kinds  of 
adventitious  dentines,  already  fully  described,  occur.     It  is  unnec- 

174 


INJURIES    OF    THE    DENTAL    PULP  1 75 

essary  to  lay  stress  on  the  fact  that  here,  as  elsewhere,  the  process  is 
essentially  similar.  Osteoblasts,  which  are  the  great  factors  in  the 
production  of  bone,  are  not  found  in  the  pulp;  but  the  dento-genetic 
cells,  with  which  the  tissue  is  freely  supplied,  do  similar  work.  When 
the  pulp  is  nearly  exposed,  for  instance,  they  combine  to  repair  the 
damage  done  by  caries.  Examples  of  "dentine  of  repair"  are  often 
seen.  In  traumatism,  too,  the  process  is  exactly  the  same  as  when 
a  tissue  has  been  wounded,  and  has  been  kept  in  an  aseptic  condition, 
and  properly  protected  from  certain  infective  processes.  In  these 
cases  the  method  of  repair  is  known  as  "healing  by  the  second  inten- 
tion," or  granulation.  A  third,  but  exceedingly  rare  class  of  cases, 
where  a  tooth,  having  been  fractured,  and  the  parts  kept  at  rest 
until  union  has  been  effected,  supplies  an  example  of  "healing  by  the 
third  intention."  Cemental  or  dentinal  union  is  only  possible,  it  is 
obvious,  when  pulp  or  periodontal  membrane,  or  both,  have  received 
an  injury  which  has  not  destroyed  their  reparative  powers,  but  which 
has  induced  a  slight  or  sub-acute  form  of  inflammation,  and  thus 
stimulated  the  active  cells  to  perform  their  functions. 

These  notes,  however,  are  not  intended  to  generalise  altogether, 
but  to  particularise,  and  to  sum  up  what  is  known  of  some  of  the 
healing  processes  in  the  pulp. 

It  will  be  convenient,  then,  to  consider  the  subject  from  several 
points  of  view; — (i)  When  a  minute  area  of  the  pulp  tissue  has  been 
injured;  (2)  when  a  large  surface  has  been  trauma tically  exposed; 
(3)  ordinary  exposure  of  the  pulp  by  the  action  of  caries;  (4)  frac- 
ture of  teeth  with  or  without  impaction  of  the  fragments;  and  finally 
(5)  in  cases  of  non-exposure  of  the  pulp. 

HISTOLOGY 


When  a  minute  area  of  the  pulp  has  been  injured. 

It  is  not  difficult  to  conceive  of  a  simple  traumatic  inflammation 
of  the  pulp  being  set  up  when  a  small  traumatic  exposure  has  been 
made,  which  has  been  immediately  followed  by  the  penetration  (and 
therefore  wounding)  of  the  soft  tissues  by  means  of  a  fine  point  like 
that  of  a  bristle.  The  picture  that  can  be  drawn  of  this  rather  hy- 
pothetical state  of  things  is  quite  clear,  from  one's  knowledge  of 
wounds  generally. 

The  capillaries,  together  with  the  small  arteries  and  veins  in  the 
coronal  region,  woulrl  be  divided,  causing  momentary  haemorrhage, 


176 


THE   DENTAL   TISSUES 


which  soon  ceases  in  consequence  of  stasis  and  coagulation  of  the 
blood.  Dilatation  of  the  vessels  in  the  neighbourhood  with  relaxed 
flow  of  their  blood-currents  next  supervenes,  leucocytes  and  liquor 
sanguinis  escape  from  their  walls,  and  the  cellular  elements  around 
undergo  sub-division  and  proliferation.  Lymph  in  minute  quantities 
is  poured  out,  and  contains  fibrin  and  blood  corpuscles;  the  serum 
becomes  absorbed  and  approximation  of  the  divided  surfaces 
results.  Outside  the  region  of  the  wound  the  vessels  are  dilated, 
but  the  rate  of  the  flow  of  blood  is  increased.     Shortly  after  the 


Fig.  176. — Coagulation  necrosis  and  fatty  necrobiosis  of  the  superficial  por- 
tions of  the  pulp  occurring  after  a  chemical  injury  of  twelve  hours'  duration, 
following  a  sub-acute  inflammation  of  the  pulp.  Stained  with  hasmatoxylene 
and  eosine.      Magnified  200  times. 

injury,  the  exudate,  which  has  coagulated,  more  or  less,  is  removed 
and  replaced  by  small  rOund  cells  derived  from  the  infiltrating  leu- 
cocytes and  proliferating  connective-tissue  cells,  and  thus  adhesion 
of  the  separated  parts  takes  place.  Finally,  delicate  loops  of  new 
capillaries  emanating  in  their  origin  from  the  old  vessels  spread  across 
the  parts,  and  anastomosing,  restore  the  vascularity  of  the  tissues, 
and  repair  the  lesion  by  the  production  of  fibrous  bands  and  ulti- 
mately a  small  cicatrix. 

Such  a  condition  of  things  could  only  be  accomplished  when  the 
pulp  was  only  slightly  injured;  when  the  foreign  body  producing  the 


INJURIES    OF    THE    DENTAL    PULP  1 77 

injury  was  not  septic;  and  when  tlie  cavity  in  tlie  dentine  liad  been 
treated  by  strictest  antiseptic  measures. 


Wlien  a  large  area  of  tlie  pulp  surface  has  been  traumatically 
exposed,  as  occurs  during  fracture  of  the  crown  of  a  tooth  in  an 
attempted  extraction,  regional  hypergemia  occurs  and  inflamma- 
tory symptoms  are  set  up.  Many  interesting  microscopical  struc- 
tures are  now  brought  to  light. 

If  sections  are  made  within  twelve  hours  of  the  accident — or  rather 
if  the  preparation  of  the  tissues  for  section  cutting  is  begun  within 
twelve  hours — the  pulp  will  be  found  to  be  crowded  with  small  round 
cells.  These  comprise  the  infiltrating  leucocytes  and  proliferating 
connective-tissue  cells.  The  odontoblasts  are  profoundly  altered 
in  shape,  being  flattened  and  compressed  on  to  the  dentinal  walls 
through  the  swelling  and  exudation  of  the  inflammatory  processes. 
They  have  also  undergone  mytosis  and  are  numerically  multiplied. 
The  vessels  are  actively  hypersemic,  and  in  the  radicular  portions  of 
the  pulp  are  largely  thrombosed.  On  the  free  surface  of  the  pulp 
an  attempt  at  healing  has  occurred,  organisation  of  the  exudative 
fluids  and  materials  having  taken  place.  Blood  cells,  escaped  from 
the  broken  coronal  capillaries,  are  caught  and  retained  in  the 
meshes  of  a  fine  fibrous  stroma  of  new  formation.  The  cells  are  very 
greatly  disintegrated,  and  probably  many  of  them  have  been  con- 
verted into  pus  corpuscles.  Probably,  too,  coagulation  necrosis 
and  fatty  necrobiosis  of  the  superficial  tissues  have,  to  a  certain 
extent,  taken  place,  as  there  are  some  appearances  of  fibrin  forma- 
tion as  well  as  degenerative  lipogenesis  in  the  midst  of  the  tissues 
(see  Fig.  176).  It  is  unlikely  that  micro-organisms  would  produce 
liquefaction  of  the  parts  in  so  short  a  space  of  time  as  twelve  hours, 
especially  as  a  thick  blood-clot  would  have  protected  the  free  surface 
from  the  oral  secretions.  It  is  almost  certain  that  if  liquefaction  of 
the  necrotic  tissue  and  the  solid  exudates  has  occurred  it  is  due  to 
proteolytic  enzymes. 

On  examining  sections  where  a  similar  lesion  had  occurred  seven 
days  previously,  but  few  fresh  changes  are  noticed.  The  free 
surface  is  covered,  as  before,  with  many  layers  of  disintegrated 
cells,  including  pus  cells.  Traces  of  the  original  inflammation  have 
more  or  less  disappeared  and  new  capillaries  abound,  freely  vascu- 
larising  the  part.     But  one  notices  everywhere,  and  especially  in 


178 


THE    DENTAL    TISSUES 


the  cervical  and  radicular  regions,  new  deposits  of  soft  calcific  ma- 
terial in  the  midst  of  the  tissues.  These  have  the  same  appear- 
ance as  that  shown  in  Fig.  170.  The  laying  down  of  calco-globulin 
is  a  favourite  method  of  repair  on  the  part  of  the  pulp.     Whence 


Fig.  177. — Freshly  deposited  calcific  nodules  in  the  pulp,  showing  the  method 
of  formation.  Prepared  by  the  Author's  process.  Stained  with  borax-carmine. 
Magnified  50  times,  p.d.  Primary  dentine  of  the  tooth;  N.  Formed  and  calcified 
dentine  nodules  incorporated  in  the  walls  of  the  pulp  cavity;  f.n.  Nodule  formed 
but  not  yet  calcified;  F.  Connective  fibrous  stroma  with  dentogenetic  cells,  about 
to  form  the  calcified,  masses;  p.  Pulp  tissue  with  nerve  bundles  and  blood-vessels; 
A.  Pulp  near  apical  region. 


F  N 


come  these  new  masses?  How  are  they  brought  into  existence? 
What  laws  govern  their  formation?  These  are  questions  which 
one  finds  considerable  difficulty  in  answering  satisfactorily.  It  is 
unlikely  that  they  are  due  to  the  local  enzymes  of  micro-organisms. 


INJURIES    OF    THE    DENTAL   PULP 


179 


or  that  they  are  found  congregated  around  masses  of  bacteria.  They 
are  not  always  dependent  on  being  closely  approximated  to  vessel 
walls,  for  they  are  seen  in  other  situations.  Black^  inclines 
to  the  belief  that  the  formation  of  these  masses  is  due  to  a  condi- 
tion of  congestion  or  venous  hypersemia  of  the  pulp.  He  compares 
them  to  the  phleboliths  found  in  varicose  veins,  and  suggests  that 
in  these  congested  veins  there  may  exist  the  three  conditions,  or 
factors,    necessary   for    the   production    of    calcospherite    globules. 


FN 


C  TF 


Fig.  178. — An  early  stage  in  the  formation  of  nodules  of  calcific  material  in 
the  pulp.  Shows  methods  of  formation.  Prepared  as  in  the  preceding  figure. 
Stained  with  orange  rubine.  Magnified  250  times,  f.n.  Nodule  undergoing 
calcification;  N.  Nuclei  of  the  formative  cells;  c.t.f.  Connective  tissue  fibres; 
M.N'.   Myelinic  nerve  bundle;  c.    Capillary;  p.  Pulp  tissue  proper. 


viz.,  the  presence  of  carbonic  acid  in  association  with  salts  of  lime 
and  albumen.  Similar  views  have  been  recently  expressed  bv  Wood- 
head  in  a  paper  on  Calcification. 

It  seems  probable  and  possible  that  these  nodes  are  produced 
solely  by  the  pouring  out  of  calcific  matters  by  the  dentogenetic 
cells  of  the  pulp,  which  take  on  a  catagmatic  function  identical  with 
that  of  the  osteoblasts  in  the  formation  of  callus.  It  is  probable 
that  this  phenomenon  occurs  in  the  case  of  the  growth  of  ''pulp 

1  "American  System  of  Dentistry,"  vol.  i.,  p.  862. 


l8o  THE    DENTAL    TISSUES 

nodules"    and   during  calcareous  degeneration  of  the  pulp.     And 
if  so  there,  why  not  here? 

That  the  process  must  be  somewhat  of  this  nature  would  seem 
to  be  confirmed  by  the  interesting  case  fully  reported  by  C.  S.  Tomes, 
and  published  in  the  Transactions  Odonto.  Soc.  of  Great  Britain, 
pp.  184-5-6,  1896.  Of  such  importance  this  would  apparently  be, 
that  no  excuse  is  needed  to  here  add  Tomes'  description.  The 
tooth,  a  mandibular  molar,  had  been  fractured  during  attempted 
extraction  three  years  before  removal  of  the  root.  The  pulp  cavity 
was  then  seen  to  be  occupied  by  a  "cauliflower-shaped  mass  of 
■shining  polished  ivory  projecting  above  the  original  surface  of  frac- 
ture and  overflowing  on  to  it."  The  pulp  was  only  partially  cal- 
cified, the  lowest  radicular  portion  containing  sentient  tissue.  The 
large  mass  of  newly  formed  material  was  closely  coherent  to,  and 
contiguous  with,  the  old  dentine. 

Histologically  speaking,  a  cursory  inspection  of  its  structure 
showed  a  free  surface  with  laminae  running  parallel  with  the  sur- 
faces. A  series  of  lacunal  spaces  came  below,  then  a  few  dentinal 
tubes,  and  finally  in  the  deepest  portion,  numerous  dentinal  tubes 
which  were,  in  some  places,  continuous  with  the  tubes  of  the  pri- 
mary or  original  dentine.  The  outgrowth  of  hard  tissue  contained 
embedded  in  it  several  detached  and  displaced  splinters  of  the 
primary  dentine. 

The  following  are  details: — - 

'TAe  Laminated  Outer  Layer. — This  consists  of  laminae  parallel 
with  the  surface,  and  varies  in  thickness  reaching  in  places  3'^5o 
inch,  and  containing  about  ten  well-marked  layers.  Here  and  there 
it  constitutes  the  whole  of  the  overflow,  and  it  contains  some  canal- 
iculi,  taking  a  direction  perpendicular  to  the  surface,  and  a  few 
well-formed  lacunae  with  their  canaliculi.  It  is  present  every- 
where, though  its  amount  and  the  distinction  of  the  lamination  are 
variable. 

"  The  Lacunal  and  Interglobular  Spaces. — The  tissue  immediately 
below  the  laminated  layer  is  characterised  by  an  immense  number  of 
lacunae  and  interglobular  spaces,  which  are  in  parts  well  formed,  and 
in  other  parts  very  coarse  and  irregular.  The  fine  boundary  of  this 
region  of  lacunal  spaces  is  in  places  well  defined,  and  terminates 
with  bodies  of  the  "encapsuled  lacuna"  type;  elsewhere  it  passes 
insensibly  into  the  region  occupied  by  tubes,  in  the  outer  part  of 
which  latter  region  interglobular  spaces  are  abundant,  and  are 
somewhat  irregularly  disposed. 


INJURIES    OF    THE    DENTAL   PULP  l8l 

''The  Tube  System. — In  the  centre  of  the  tooth  the  tubes,  Uke 
those  of  normal  dentine,  run  vertically  upwards  towards  the  surface, 
w^hile  towards  the  sides  of  the  new  mass  they  radiate  outwards, 
passing  thus  beyond  the  Hmits  of  the  fractured  primary  dentine, 
and  spreading  themselves  fanlike  over  the  edges  of  the  original 
tooth  to  a  certain  extent.  In  that  portion  of  the  newly  formed 
dentine  which  lies  within  the  original  dentine,  and  which  latter 
constituted  originally  the  lateral  walls  of  the  pulp  cavity,  the 
tubes  run  more  or  less  outwards,  and  are  joined  up  into  con- 
tinuity with  the  old  dentinal  tubes,  there  being  generally  an  abrupt 
bend  and  some  dilatation  at  the  junction.  From  an  inspection  of 
the  sections  it  will  thus  be  seen  that  the  whole  boundary  of  the 
resultant  pulp  cavity,  formed  at  its  sides  and  below  by  the  original 
dentine,  and  above  by  the  new  dentine,  is  formed  of  dentinal  tubes 
of  normal  appearance,  and  that  the  pulp,  though  diminished  in 
bulk,  has  almost  perfectly  normal  surroundings  over  nearly  its 
whole  area. 

"As  the  tubes  run  outwards  they  become  more  widely  separated 
owing  to  their  fanlike  spreading:  it  is  noteworthy  that  there  are  not 
a  greater  number  of  tubes  in  the  expanded  portion,  but  that  the 
interstices  between  them  become  larger.  A  good  many  lateral 
branches  are  given  off,  such  as  those  which  occur  abundantly  in  the 
dentine  of  roots  of  normal  teeth.  Towards  their  outer  extremities 
many  of  the  tubes  show  longitudinal  dilatations,  and  are  joined  up 
to  the  canahcuH  of  lacunal  spaces;  some  end  in  brush-like  expan- 
sions, while  others  terminate  in  loops,  the  loops  being  common  to  two 
or  more  tubes;  others  are  sharply  bent  back  on  themselves.  At  and 
above  the  ends  of  the  tubes  fine  globular  formations  may  here  and 
there  be  very  distinctly  seen. 

"  The  Included  Splinters  of  Dentine. — As  has  already  been  mentioned 
this  specimen  is  probably  unique  in  that  the  newly  formed  dentine 
contains  quite  a  number  of  little  detached  pieces  of  the  original 
dentine  of  the  tooth  which  were  splintered  off  in  the  original  attempt 
at  extraction,  and  which  have  become  sohdly  enclosed  in  the  new 
formation.  They  have  been  displaced  in  various  ways  so  that  their 
tube  systems  run  in  all  sorts  of  directions,  and  are  in  no  way  con- 
formable with  the  tubes  of  the  new  growth.  But  they  have  in  their 
irregularity  of  position,  this  much  in  common,  that  the  tubes  of  the 
new  growth  when  they  are  of  any  size,  do  not  pass  beyond  them,  but 
terminate  beneath  them.  To  this,  however,  there  are  some  excep- 
tions, where  quite  small  chips  appear  to  have  been  driven  more 


l82  THE    DENTAL    TISSUES 

deeply  into  the  pulp.  Upon  the  whole,  then,  it  may  be  said  that  the 
broken  fragments  of  old  dentine  either  lie  embedded  in  the  region 
of  lacunal  spaces,  or  between  this  and  the  commencement  of  the 
tube  system.  It  is  not  a  little  remarkable  that  none  of  the  frag- 
ments show  the  least  sign  of  absorption,  but  that  their  edges  are 
left  quite  angular,  just  as  if  they  were  broken  off.  Where  the  tubes 
commence  close  against  the  fragments,  they  are  bent  about,  obviously 
with  relation  to  the  included  pieces. 

"Marks  of  Absorption. — It  is  notable  that  notwithstanding  the 
violent  irritation  to  which  the  pulp  was  subjected,  in  very  few  places 
can  any  marks  of  absorption  be  found.  "The  occurrence  of  'en- 
capsuled  lacuna-Hke'  forms  has  already  been  mentioned  where  the 
lacunal  region  merges  into  that  of  well-formed  tubes,  but  a  few  marks 
of  absorption  and  subsequent  calcification  are  to  be  found  elsewhere 
and  in  unlikely  places.  Thus  under  the  calcified  overflow  are  some 
pits  occupied  by  Howship's  lacunae. " 

Here  is  a  history  of  the  injury  extending  over  a  period  of  three 
years — it  is  not  a  question  of  hours  or  weeks;  and  so  it  would  appear 
that  the  two  cases  previously  quoted  might,  had  time  been  allowed 
and  all  conditions  favourable,  have  succeeded  in  developing  into 
complete  calcification  of  the  pulp,  not  by  the  conversion  of  blood-clot 
or  organisation  of  the  inflammatory  products  necessarily,  but  simply 
by  a  conversion,  or  secretion  or  excretion  of  the  lime-bearing  cells  of 
the  pulp  into  one  united  mass;  in  other  words,  the  calcification  of  a 
plastic  exudation.  It  is  true  that  no  cell  of  this  description  has  ever 
been  seen  depositing  this  material  in  the  form  of  calco-globuHn;  but 
it  is  quite  easy  to  understand  that  as  a  result  of  pathological  changes 
in  the  dentine,  these  small  cells  may  be  stimulated  to  exercise  their 
functions  of  abstracting  the  lime  salts  from  the  blood  in  the  pulp, 
manufacturing  them  again  in  the  cell-cytoplasm,  and  ultimately 
pouring  them  forth  when  their  work  is  done. 

3 
Again,  exposure  of  the  pulp  through  caries  leads,  as  is  well  known, 
to  inflammation.  This  may  be  so  severe  as  to  cause  death  of  the 
pulp,  whose  unyielding  environment  prevents  much  swelling  and  the 
free  discharge  of  accumulated  inflammatory  products.  Restorative 
processes  are,  however,  often  brought  about,  and  the  result  is  the 
formation  of  a  so-called  "polypus"  of  the  pulp.  The  term  "poly- 
pus" is  an  incorrect  appellation,  and  as  such  ought  to  be  deleted 
from  dental  terminology  (see  page  165). 


INJURIES    OF    THE    DENTAL   PULP  1 83 

The  formation  of  a  protective  covering  by  the  extension  and 
growth  of  squamous  epithehal  cells  on  the  free  surface  of  the  exposed 
tissue  must  certainly  be  considered  as  another  attempt  at  healing, 
and  might  almost  be  a  modification  of  autoplasty.  For  chronic 
inflammation  of  the  pulp,  with  an  epithelial  surface,  may,  and  often 
does,  remain  in  a  carious  tooth  for  months  and  years  without  any 
discomfort  to  the  individual.  Probably  the  reparative  process  is 
most  complete  when  the  new  tissue  assumes  the  form  not  merely  of 
several  layers  of  stratified  squamous  epithelium,  but  dips  down  into 
the  granulations  and  gives  to  their  surface  the  shape  of  simple  or 
compound  papillae.  This  produces  a  thicker  envelope,  and  affords 
greater  protection  to  the  soft  subjacent  structures. 


Perhaps,  after  all,  the  methods  of  healing  of  wounds  of  the  pulp 
are  better  illustrated  in  cases  of  those  fractures  of  the  teeth  where  the 
parts  have  been  kept  in  situ  for  some  period  of  time  subsequent  to 
the  accident.  And  one  may  cite,  in  addition  to  Tomes'  unique 
specimen,   three  more  cases  which  have  been  recently  reported. 

In  the  first-mentioned  patient — a  girl,  aged  14 — an  incisor  was 
fractured  longitudinally  and  impacted.  It  was  thought  that  union 
would  be  established  either  through  the  medium  of  the  pulp  or 
periodontal  membrane.  Here,  however,  probably  from  the  mo- 
bility of  the  fragments,  the  pulp  became  inflamed,  fungated,  and 
finally  calcified.  Thus  healing  of  the  pulp  lesion  occurred,  although 
union  of  the  hard  parts  was  not  established. 

In  a  second  interesting  case  several  features  were  noticed.  The 
tooth,  also  a  maxillary  incisor,  was  not  impacted,  and  there  was  no 
ultimate  union.  Under  the  microscope  the  margins  of  the  pulp 
canal  showed  traces  of  absorption,  Howship's  foveolse  being 
strongly  pronounced.  These  areas  of  absorption  were  filled  with  a 
layer  of  new  dentine,  which  at  the  extreme  apex  of  the  root  was 
homogeneous — like  the  matrix  of  hyaline  cartilage — and  cellular, 
higher  up,  an  intermediate  kind  of  irregular  fibrillar  dentine  inter- 
vening. The  pulp  at  the  free  margin  of  the  upper  fragment  was 
enlarged  and  chronically  inflamed,  being  unusually  fibrous  in 
character.  How  can  the  presence  of  these  new  dentines  in  the  root 
canal  be  interpreted?  Obviously,  a  healing  process,  which,  if 
allowed  to  continue,  would  have  finally  obliterated  it  with  a  hard 
mass  of  new  dentine. 


i84 


THE   DENTAL   TISSUES 


Figs.  179  and  180. — Outer  halves  of  an  impacted  united  maxillary  incisor. 
The  sagittal  section,  from  which  Fig.  181  is  taken,  was  the  central  portion  of  the 
tooth.  These  and  the  three  following  photographs  are  from  specimens  in  the 
collection  of  F.  J.  Bennett. 


Fig.   181. — Sagittal  section,  showing  the  parts,    e.  Enamel;  d.   Dentine;  p.  Pulp 
cavity;  O.   New  ossified  material  which  acted  like  a  definitive  callus. 


INJURIES    OF    THE    DENTAL   PULP 


185 


The  case  presented  somewhat  similar  features  to  that  of  another 
case  of  impacted  fracture  of  a  canine,  save  that  in  the  latter  the 
calcified  uniting  portion  was  the  product,  most  probably,  of  the 
cells  of  both  pulp  and  periodontal  membrane,  a  genuine  example  of 
autoplasty. 

This  specimen  was  one  of  profound  interest. 

The  history  showed  that  an  oblique  fracture  of  a  tooth  and  im- 
paction of  one  of  its  fragments  had  remained  in  situ  for  ten  months. 
Intense  pain  led  to  its  ultimate  removal  from  the  mouth. 


Fig.    182. — Low  power  magnification  of  the  intervening  uniting  tissue. 

The  fragments  were  united  by  some  dense  calcified  material 
which  spans  the  intervening  space  (see  Figs.  181,  182  and  183). 
The  margins  of  the  space  were  uncalcified.  The  catagmatic  ma- 
terial consisted  of  spongy  or  cancellous  osseous  substance,  freely 
supplied  with  blood-vessels.  The  edges  of  the  primary  dentine 
showed  signs  of  absorption  and  subsequent  deposition  of  a  cemen- 
tum-like  material. 

The  probable  explanation  of  the  pathological  changes  which  pro- 
duced such  an  excellent  union  may  be  described  as  follows:- — It 
is  "a  case  in  which,  haemorrhage  having  taken  place,  a  natural  cap- 
ping of  the  exposed  pulp  occurred,  somewhat  similarly  to  the  way 


i86 


THE   DENTAL   TISSUES 


a  wound  heals  under  a  scab.  Blood  was  poured  out  between  the 
fragments,  organisation  took  place,  numerous  blood-vessels  were 
produced,  and  ultimately  calcification  occurred;  and,  eventually,  if 
it  had  been  left  long  enough,  the  whole  of  the  space  would  probably 
have  been  filled  up  with  calcified  material  more  or  less  resembling 
bone,  or  bone  and  cementum  together"  {Trans.  Odonto.  Soc.  of 
Great  Britain,  April,  1896). 

Finally  (5)  little  need  be  said  here  with  regard  to  the  last  di- 
vision of  this  subject,  viz.,  those  cases  of  non-exposure  of  the  pulp, 


Fig.    183. — Higher  power  of  the  same. 

because  the  question  has  been  discussed  in  the  preceding  Chapter, 
and,  it  may  be  added,  is  still  incompletely  investigated.  Sufiice  it 
to  draw  attention  to  the  fact  that  the  inroads  made  by  caries  in  the 
dentine  and  enamel  is  counter-balanced  in  the  pulp  by  the  produc- 
tion of  several  different  kinds  of  adventitious  dentine,  and  that 
both  early  and  later  lesions  of  the  hard  parts  are  nearly  constantly 
associated  with  the  development  of  new  dentines,  and,  therefore, 
with  one  of  the  most  interesting  methods  of  repair  of  the  tissues 
of  the  pulp. 


CHAPTER  VII 
THE  DEGENERATIONS  OF  THE  DENTAL  PULP 

Microscopical  Elements  in: — (i)  Fibroid;  (ii)  Atrophic;  (iii)  Fatty,  and 
(iv)  Calcareous  Degenerations. 

GENERAL    CHARACTERISTICS 

As  a  result  of  various  conditions,  the  pulp  is  exceedingly  liable  to 
undergo  degenerative  changes.  The  most  common  is  calcareous, 
because  of  the  great  tendency  for  this  organ  to  repair  any  breach  of 
its  surface,  which  has  been  made  by  cariousor  other  morbid  processes. 

If  a  tooth  has  persisted  for  years,  and  has  withstood  all  attacks  of 
a  traumatic,  chemical  or  carious  origin,  its  pulp  will,  under  favourable 
circumstances  become  sclerosed  and  fibrillar,  if  not,  it  will  probably 
undergo  calcareous  or  other  atrophic  changes.  It  is  necessary  to 
consider  these  conditions  somewhat  in  detail: — 

1.  Fibroid  degeneration. 

2.  Atrophic  degeneration. 

3.  Fatty  degeneration. 

4.  Calcareous  degeneration. 


Fibroid  Degeneration 

Whilst  studying  the  histology  and  histo-pathology  of  the  dental 
pulp  in  its  normal  relationship  to  dentine,  and  preparing  sections  of 
human  teeth  with  this  object  in  view,  the  author  found  among  his 
sections  some  excellent  and  remarkable  examples  of  fibrosis  or  fibroid 
degeneration.  The  typical  appearances  presented  on  microscopic 
examination  of  these  specimens  warranted  more  than  a  passing  notice : 
and  as  they  were  further  investigated,  they  became  more  and  more 
interesting,  sufficiently  justifying  an  accurate  description  and  a  care- 
ful account  being  placed  on  record. 

Definition. — ^Later  it  will  be  clearly  shown  that  the  term  ''fibrosis" 
or  fibroid  degeneration  is  the  only  one  which  can  with  certainty  be 

187 


THE   DENTAL    TISSUES 


applied  to  this  particular  form  under  notice.  That  it  is  an  example 
of  degeneration  there  is  no  doubt,  and  it  is  equally  easy  to  eliminate 
those  other  degenerative  varieties — such  as  mucous,  calcareous  or 
fatty,  which  animal  tissues  may  undergo. 


Fig.  184. — Vertical  section  of  fibroid  degeneration  of  the  pulp  in  situ.  Pre- 
pared by  the  Author's  process.  Stained  with  acid  rubine.  Magnified  45  times. 
D.  Dentine;  p.  Pulp  tissue;  s.  Circular  spaces  cut  longitudinally ;  F.  Dense  strands 
of  strong  coarse  fibres. 


Etiology. — The  present  instance  affords  an  opportunity  of  ex- 
amining certain  structural  metamorphoses  in  the  pulp  which  are 
believed  not  to  be  dependent  on  any  inflammatory  condition,  but 
simply  attendant  on  and  produced  by  senile  constitutional  changes. 
Further  investigations  will  go  to  prove  that  it  is  a  natural  old-age 
termination  of  the  life  of  a  healthy  pulp. 


THE  DEGENERATION  OF  THE  DENTAL  PULP       1 89 


FO 


Fig.  185. — Fibroid  degeneration  of  the  pulp  of  a  deciduous  tooth.  Stained 
with  hsematoxylene.  Magnified  45  times,  p.d.  Primary  dentine;  a.d.  Hyaline 
adventitious  dentine;  A.  Absorption  of  primary  dentine;  f.o.  Fibroid  odonto- 
blasts; B.  Blood-vessel;  N.  Nerve  bundle.  The  degeneration  is  complete  at  the 
lower  part  of  the  figure. 


I  go 


THE    DENTAL    TISSUES 


This  affection  seems  to  have  been  unknown  to,  or  overlooked^by 
the  dental  pathologists  of  the  Continent  and  America,  for  though 
Arkovy,  Magitot,  Rothmann  and  Black,  publish  minute  descriptions 
of  the  patho-histology  of  the  dental  pulp  and  periosteum,  and 
elaborate  dissertations  on  ulcers  and  tumours  connected  therewith, 
in  no  instance  does  one  find  an  account  of  the  senile  variations  in  the 
tissues  of  a  tooth.  Black,  in  the  "American  System  of  Dental 
Surgery"  (Vol.  i.,  p.  859),  figures  and  describes  an  areolation  of  the 
pulp,  which  at  first  sight  resembles  fibrification  of  that  tissue,  but 
differs  very  materially  from  it  in  the  fact  that  numerous  cells  and 


D  o 


Fig.  186. — Fibroid  degeneration  of  the  pulp.  Prepared  and  stained  as  in 
the  preceding  figure.  Magnified  250  times,  d.  Dentine;  d.O.  Degenerate  odon- 
toblasts; p.  Pulp  tissue  proper. 


nuclei  are  present  in  the  sections  from  which  he  draws  his  conclusions. 
He  writes: — "Areolae  develop  in  the  matrix,  and  all  the  histological 
characters  of  the  tissues  are  profoundly  changed.  These  areolae 
were  evidently  filled  with  fluid;  hence  a  kind  of  oedema  of  the  organ 
must  have  existed,  which,  in  the  enclosed  pulp-chamber,  has  prob- 
ably gradually  destroyed  the  cellular  elements;  and  new  elements 
thrown  out  in  the  inflammatory  process,  have  suffered  the  same 
fate." 

Of  the  pathology  and  clinical  histories  of  the  teeth,  the  histology 


THE  DEGENERATION  OF  THE  DENTAL  PULP       IQI 

of  which  is  presently  to  be  described,  little  need  be  said.  The  teeth 
from  which  the  sections  were  taken  were  chiefly  maxillary  canines 
and  premolars,  apparently  sound,  but  useless,  inasmuch  as  they  had 
been  loosened  by  the  gradual  absorption  of  their  alveolar  bone, 
which  had  left  the  portion  below  the  neck  exposed.  As  a  result, 
there  had  occurred  that  peculiar  periostitic  pain,  or  something 
analogous,  so  often  noticed  in  elderly  patients  with  absorbed  sockets, 
and  the  teeth  were  extracted.  They  occurred  in  the  mouths  of 
different  patients.  Of  a  dark  yellow  colour,  they  presented,  in 
addition,  all  the  appearances  of  the  changes  of  senihty. 

Similar  conditions  in  the  deciduous  teeth  of  children  have  been 
noticed. 

A  good  number  of  longitudinal  and  transverse  sections,  suitable 
for  microscopic  examinations,  were  obtained.  The  revelations  af- 
forded by  these  sections  are  of  a  particularly  interesting  nature. 

Secondary  Changes. — None. 

HISTOLOGY 

It  is  evident  that  in  complete  pulpar  fibrosis  no, cellular  elements  of 
any  description  whatever  occur.  This  is  clear  at  once,  and  is  an 
important  fact.  No  trace  of  cellular  organisation,  no  vestige  of 
cell  nuclei,  no  remains  of  interstitial  cement  substance  can  be  found 
anywhere.  Nerves,  cells,  blood-vessels,  odontoblasts,  have  alike 
shared  the  process  of  fibrification,  and  are  no  longer  recognisable, 
and  the  connective  tissue,  which  is  but  a  loose  mass  of  network  in  the 
normal  state,  has  either  become  grossly  hypertrophied  or  quite  obHt- 
erated,  and  its  place  taken  by  a  new,  firm,  fibrous  structure,  devoid 
of  cells,  nuclei,  or  any  regular  arrangement  of  constituent  parts. 

In  a  longitudinal  section  which  is  viewed  under  low  magnifica- 
tion, the  appearances  much  resemble  pulmonary  tissue,  minus 
cells.  The  pulp  seems  to  consist  of  retiform  connective  tissue, 
containing  large  alveolar  spaces,  with  here  and  there  long  cylin- 
drical cavities,  all  having  extremely  thin  walls.  Several  of  these 
tubes  are  shown  in  Fig.  184;  they  are  probably  the  fibrous  remains  of 
what  once  were  blood-vessels.  The  dentinal  surface  of  the  pulp  is 
occupied  by  a  more  highly  defined  appearance.  Rows  of  long,  thick 
fibres  of  various  shapes  and  sizes,  some  bifurcated,  others  plain,  and 
again  some  possessing  fibrous  off-shoots,  are  here  distinctly  seen, 
attached  to,  and  in  places  detached  from  the  dentine.  In  those 
situations  where  the  fibres  adhere,  curious  dark  markings,  extending 


192 


THE   DENTAL   TISSUES 


Fig.  187. — Horizontal  section  of  fibroid  degeneration  of  the  pulp  in  situ 
Prepared  and  stained  as  in  Fig.  184.  Same  magnification.  D.  Deeply  stained 
dentine;  s.  Large  areolar  spaces;  d.o.  Degenerate  odontobasts;  p.  Fibroid  tissue 
of  the  pulp. 


THE  DEGENERATION  OF  THE  DENTAL  PULP      1 93 

in  the  direction  of  the  Hnes  of  the  tubules,  are  visible  in  the  dentine; 
they  are,  without  doubt,  due  to  the  retention,  in  situ,  of' the  dentinal 
fibrils,  which  give  to  them  a  different  refractive  index  to  that  of 
the  empty  tubes.  These  are  well  demonstrated  in  the  sections  from 
which  Figs.  184  and  186  are  taken.  The  row  of  fibres  represents 
the  pre-existing  odontoblasts.  This  is  proved  by  the  following 
points: — (i)  They  distinctly  occur  at  the  edge  of  the  pulp,  in  the 
site  occupied  normally  by  the  memhrana  ehoris;  (2)  They  are  con- 
tinued into  the  tubules  of  the  dentine,  in  a  similar  manner  to  that 
of  the  processes  of  the  odontoblasts;  (3)  At  the  coronal  portion  of 
the  pulp,  the  fibres  are  larger,  stronger,  more  marked,  and  less  nu- 
merous than  elsewhere;  and  (4)  Their  method  of  attachment  to 
the  main  parts  of  the  pulp  closely  approximates  to  that  which  ob- 
tains in  the  normal  odontoblasts.  Hence  it^is  that  these  fibres, 
with  their  marked  outHnes,  are  degenerate  and  fibroid  odonto- 
blasts, but  so  altered  in  shape  and  size  as  to  appear  to  be  merely 
bundles  of  connective  tissue,  which  penetrate  the  dentine  to  a  vari- 
able extent. 

On  examining  transverse  sections,  several  curious  formations  are 
noted.  First,  it  is  observed  that  there  may  be  considerable  fi- 
broid shrinkage  of  the  pulp,  and  separation  from  one  side  of  the  pulp 
cavity,  as  in  Fig.  187,  or  not  so  much  atrophy  as  in  Fig.  188.  In  the 
first  instance,  it  is  perfectly  obvious  that  this  shrinkage  has  not  been 
caused  by  the  mode  of  preparation  to  which  the  tooth  Was  subjected; 
it  is-  a  natural  and  fibroid  contraction  of  the  pulp,  produced  by  a 
gradual  knitting  together  of  the  fibrous  tissues,  which  have  become 
on  one  side  detached  entirely  from  the  hard  dentinal  wall,  in  conse- 
quence of  the  unyielding  nature  of  the  latter.  A  large  conspicuous 
chain  of  areolar  spaces  is,  however,  the  most  striking  object  here  ob- 
served (Fig.  187).  It  stretches  without  break, ■  across  the  pulp 
chamber  from  side  to  side,  and  consists  of  groups  of  more  or  less 
circu  ar  empty  spaces,  bound  together  thickly  by  fibrous  tissue. 
The  vacuoles  vary  greatly  in  size:  the  largest  .measures  about  220/i 
in  its  greatest  length,  and  160^  in  its  greatest  width,  whilst  the  small- 
est here  seen,  which  is  also  almost  circular  in  shape,  measures 
from  5-10/i  in  diameter.  At  first  sight  these  appear  to  be  blood- 
vessels cut  transversely,  but  such  is  not  so,  as  they  do  not  possess 
their  distinctively  characteristic  walls,  neither  are  they  of  the  same 
or  even  approximate  diameters.  They  are,  therefore,  simply  long 
cylinders  with  thin  but  tenacious  boundaries.  No  attempts  at 
calcification  can  be  distinguished  in  them  anywhere;  the  stroma  in 
13 


194 


THE    DENTAL    TISSUES 


which  they  are  held  is  very  dense,  has  a  clear  fibrous  structure,  be- 
comes very  marked  in  staining,  and  consequently  is  highly  differ- 
entiated from  the  surrounding  tissue. 

It  is  probably  extreme  cases  only  that  exhibit  so  remarkably 
the  chain  of  areola.  Earlier  stages  seem  to  indicate  that  the 
fibrosis  originally  began  in  the  central  portions  of  the  pulp,  in  the 
vicinity  of  the  arterial  and  nervous  systems,  and  that  the  region  of 
the  basal  layer  of  Weil  and  the  odontoblasts  were  the  last  to  undergo 
the  metamorphosis,  as  the  cells  at  the  periphery  of  the  pulp  are  the 


Fig.  i88. — Fibroid  degeneration  of  the  pulp.  A  slightly  earlier  stage  than 
the  preceding.  Prepared  similarly.  Stained  with  Ehrlich's  acid  haematoxylene. 
Magnified  15  times.  D.  Dentine;  d.o.  Degenerate  odontoblasts;  a.  Circular 
areolar  space;  p.  Fibroid  pulp  containing  no  cells,  no  nuclei,  no  nerve  bundles 
nor  blood-vessels. 


last  to  retain  their  shape  and  nuclei  (see  Fig.  188,  which  repre- 
sents an  incompleted  stage  of  this  form  of  degeneration). 

Degenerate  odontoblasts  are  always  clearly  visible  on  the  edge 
of  the  pulp. 

It  is  worthy  of  note  that  the  lumina  of  the  dentinal  tubules 
are  in  no  way  narrowed  or  occluded  by  any  adventitious  varieties 
of  calcification. 

It  must  not  be  imagined  that  these  conditions  are  to  be  demon- 
strated  in   every   senile   tooth.     Dentine   nodules,   atrophy,   total 


THE  DEGENERATION  OF  THE  DENTAL  PULP       1 95 

disorganization,  and  a  number  of  other  pathological  states  may  be, 
and  are  often  met  with:  there  must  be  many  aberrations  from  the 
types  here  considered.  But,  given  teeth  which  have  been  healthily 
preserved  through  all  the  vicissitudes  of  life,  unattacked  by  extrinsic, 
and  unexposed  to  intrinsic  influences,  it  would  seem  that  the  above 
results  are  one  form  of  the  natural  and  usual  termination  of  the 
life-history  of  the  dental  pulp. 

The  causes  of  this  condition  are  discussed  in  Chapter  IX  {q.  v.). 

2 

Atrophy  of  the  pulp 

This  rare  condition  has  been  described  and  figured  by  Wedl.^ 
It  is  interesting  from  a  microscopical  point  of  view,  but  clinically 
it  is  indistinguishable  from  other  senile  changes. 

HISTOLOGY 

Here  a  reticulum  fills  the  pulp  cavity;  the  odontoblasts  in  early 
stages  are  shrunken;  if  the  atrophy  has  far  advanced  they  will 
have  disappeared.  The  capillaries  freely  anastomose,  and  present, 
in  places,  marked  varicosities  due  to  the  contraction  of  the  connec- 
tive tissue  stroma.  They  are  larger  than  usual,  and  have  thin 
walls.     No  nuclei  in  their  sheaths  can  be  seen. 

The  nerve  sheaths  are  fatty,  granular,  and  in  places  deposits 
of  lime  salts  cover  them.  The  tissue  in  parts  is  naturally  stained. 
This  is  due  to  escape  of  the  colouring  matters  of  the  blood.  Rounded, 
elliptical,  or  cylindrical  deposits  of  dentine  frequently  exist  in  the 
body  of  the  pulp  tissue. 

Otto  Walkhoff,  in  describing  the  photomicrographs  of  atrophy 
of  the  pulp  in  his  "Atlas  of  the  Pathological  Histology  of  the  Human 
Teeth,"  says  that  the  condition  may  be  limited  to  the  odontoblast 
layer,  vacuoles  being  found  in  the  midst  of  the  normal  healthy  tissue. 
At  the  same  time,  the  underlying  pulp  tissue  has  become  condensed 
and  permeated  with  cells,  the  vessels  are  considerably  dilated,  and 
presumably  indicate  the  extent  of  the  alterations  which  the  organ 
has  experienced.  Frequently  the  odontoblasts  fuse  into  sheaves 
or  layers,  so  that  they  can  no  longer  be  individualized  (see  Fig. 
212).  The  pulp  tissue  proper  exhibits  numerous  globular  spaces, 
and  there  is  accompanying  reticular  atrophy. 

'  "Atlas  zur  Pathologic  der  Zahne,"  Plate  IV.     Leipzig,  1869. 


196  THE    DENTAL    TISSUES 

And  Armin  Rothmann  {op.  cit.)  describes  a  sclerosed  atrophy 
of  the  pulp  {^'Atrophia  pulpcB  sderoticans''')  which  is  apparently 
a  stage,  like  the  preceding,  proceeding  to  its  complete  fibrosis. 
Thus,  the  normal  connective  tissue  fibres — fine,  delicate,  and  inter- 
lacing— have  become  coarsely  fibrillated,  and  a  simultaneous 
diminution  in  the  number  of  the  cellular  elements  has  occurred.  The 
fibres  arrange  themselves  in  narrow  layers,  which  surround  the 
calcific  deposits  in  the  sclerosed  connective  tissue.  As  the  minute 
calcareous  concretions  increase  in  size,  through  fresh  peripheral 
deposition,  so  do  they  form  confluent  masses  of  a  bright  granular 
material. 


Faity  Degeneration  of  the  Pulp 

Etiology. — This  is  said  to  be  found  in  senile  teeth,  deciduous 
teeth  which  are  undergoing  absorption,  and  in  teeth  the  pulps  of 
which  have  been  "capped." 

Macroscopical  Appearances. — To  the  naked  eye  the  pulp  appears 
to  have  diminished  in  size,  receded  from  the  margins  of  the  cavity, 
and  of  a  pale  reddish-gray  colour. 

'    '5  HISTOLOGY 

Fat  globules  are  observed,  when  examined  by  the  microscope, 
following  the  course  of  the  capillaries  and  nerves,  whose  walls  and 
sheaths  undergo  degenerative  lipogenesis. 

The  odontoblasts  are  degenerated,  and  have  become  mucoid 
or  fatty. 


Calcareous  Degenerations  of  the  Pulp 

These  are  very  frequent  accompaniments  of  inflammation  of  this 
organ  as  has  already  been  seen;  but  they  frequently  exist  also  in 
apparently  sound  teeth  unaffected  by  caries.  It  is  generally  believed 
that  a  deposition  of  calcific  material  is  found  in  the  pulps  of  elderly 
people,  and,  as  such,  is  Secondary  Dentine.  But  it  is  often  found 
in  early  adult  life,  and  in  youth,  in  sound  teeth  extracted  for  regula- 
tion purposes.  The  degenerations  have  been  divided  into  two 
classes:  ist,  in  which  the  new  material  is  unattached  to  the  walls 
of  the  pulp  cavity,  and  2nd,  where  it  is  attached. 


THE  DEGENERATION  OF  THE  DENTAL  PULP 


197 


ist. — The  unattached  deposit  of  the  lime  salts,  a  condition  which 
may  be  known  as  calcification  of  the  pulp,  may  take  the  form  of 
nodules  or  rods.  Nodules  are  said  to  be  common  in  the  teeth  of 
gouty  patients,  in  senile  teeth  affected  by  fatty  degeneration  or 


M 


Fir,.  189. — Longitudinal  section  through  the  pulp  of  a  deciduous  molar  show- 
ing calcareous  degeneration.  Stained  with  hEematoxylene.  Magnified  45  times. 
D.  Dentine;  o.  Odontoblasts;  v.  Venule;  c.  Capillary  filled  with  erythrocytes; 
M.  Masses  of  calcific  material. 


reticular  atrophy,  and  in  teeth  which  have  been  for  a  lengthy  period 
subject  to  attrition  or  abrasion.  They  may  exist  in  apparently 
healthy  teeth,  in  which  cases,  their  exact  origin  is  extremely  doubtful, 
A  pulj)  noflulc  originates  in  the  centre  of  the  pulp,  close  to  the 
vascular  system  (Figs.  190  and  192). 


198 


THE    DENTAL    TISSUES 


HISTOLOGY 

Its  true  structure  is  revealed  by  the  aid  of  the  microscope.  Under 
low  powers,  Figs.  190  and  191,  one  observes  small,  solid,  rounded, 
highly  stained  masses  occupying  the  centre  of  the  tissue,  placed 
between  the  vascular  and  nervous  systems.  They  inconveniently 
crowd  on  the  nerve  bundles,  and  if  allowed  to  increase  by  fresh 
external  depositions,  will  gradually  cause  a  mechanical  lateral 
pressure  on  these  nerve  bundles  and  induce  pain.  Under  higher 
magnifications  the  nodules  are  seen  to  be  made  up  of  matrix  and 


c  H 


p  N 


Fig.  190. — A  small  pulp  nodule  in  the  radicular  region  of  the  pulp.  Mag- 
nified IS  times,  p.  Pulp  in  situ;  p.n.  Pulp  nodule;  d.  Dentine;  h.c.  Hyper- 
plasic  cementum.     The  section  was  prepared  by  Sidney  Spokes. 

cells.  The  former  is  practically  homogeneous  in  many  sections, 
but  it  may  be  laminated  or  have  a  distinctly  fibrous  structure.  It  is 
generally  rounded  or  lobulated  in  outline,  and  has  ragged  edges  in 
sections  prepared  by  the  author's  method.  Nodules  which  have 
been  isolated  from  the  pulp  have  usually  smooth  outlines  (Fig.  195). 
The  cellular  elements  of  these  nodules  are  interesting.  Roughly 
speaking,  two  varieties  of  cells  are  discovered,  round,  nucleated 
small  cells,  and  long  fusiform  or  spindle-shaped  cells,  with  small 
nuclei.  These,  intimately  mixed  together,  are  distributed  through- 
out the  mass,  but  at  the  edges  they  are  chiefly  noticeable,  giving  a 


THE    DI'XiENERATION    OF    THE    DENTAL    PULP 


199 


P  N 


Fig.  191 . — Sagittal  section  through  a  human  permanent  canine  tooth  removed 
on  account  of  mal-position.  From  a  young  patient.  Prepared  by  Weil's 
process.  Magnified  45  times.  Shows  four  pulp  nodules  in  situ.  E.  Enamel; 
D.  Dentine;  p.  Pulp  tissue;  p.n.  Nearly  structureless  pulp  nodules.  Note. — 
The  specimen  had  remained  in  Grenacher's  alcholic  borax-carmine  for  a  period  of 
several  years,  with  the  result  that  the  fine  tubes  in  the  nodules  were  stained  by 
long  immersion  in  the  colouring  reagent. 


200 


THE    DENTAL    TISSUES 


Fig.  192. — The  formation  of  the  pulp  nodules.  Prepared  by  the  Author's 
process.  Magnified  230  times,  p.n.  Pulp  nodules;  m.n.  Myelinic  nerve  bundles; 
p.   Pulp  tissue;  C.   Capillary. 


PN 


P  N 


Fig.  193. — Longitudinal  section  of  a  pulp  containing  two  large  pulp  nodules, 
parts  of  which  are  shown.  Stained  with  hsematoxylene.  Magnified  45  times. 
P.N.  Nodules  showing  striations;  c.  Capillary;  N.  Myelinic  nerve  fibres. 


THE  DEGENERATIONS  OF  THE  DENTAL  PULP      20I 

rough  uneven  outline  to  the  nodule  (Figs.  192  and  194).     The  presence 
of  the  cells  in  the  interior  of  the  nodule  is  not  constant. 

Having  studied  these  depositions  of  lime-salts  under  many 
conditions,  and  possessing  sections  which  exhibit  various  stages  in 
their  development  and  growth,  the  author  has  come  to  the  con- 
clusion that  they  are  formed  by  a  secretion  or  conversion  of  the 
small  round  cells  of  the  pulp  (Fig.  194V  This  process  may  end  in 
the  total  obhteration  of  the  cell-wall  and  nucleus,  or  the  cell  itself 
may  persist  in  situ.     In  some  sections  the  odontoblasts  have  been 


Pig.  194. — The  method  of  construction  of  the  dentine  of  a  pulp  nodule.  Pre- 
pared by  Weil's  process.  Magnified  250  times,  d.  Formed  and  calcified 
dentine;  d.z.  Dentogenetic  zone;  r.  Round  cells  forming  the  dentogenetic  zone; 
P.   Pulp  tissue. 

caught  and  embedded  in  the  new  dentine  when  it  is  attached  to  the 
primary  or  first-formed  dentine.  Of  course,  in  the  centre  of  the  pulp, 
odontoblasts  are  non-existent,  and  consequently  are  never  found 
embedded  in  the  mass.  Moreover,  they  are  never  seen  round  its 
margins. 

The  fusiform  cells  are  entangled  in  the  secretion  which  seems 
to  have  flowed  round  them.  They,  too,  undergo  obliteration. 
Sometimes- these  completed  pulp  nodules  remind  one  of  the  cal- 
cospherite  spherules  found  occasionally  in  the  normal  tissue  of  the 


202 


THE   DENTAL    TISSUES 


periodontal  membranes  of  young  teeth.  When  quite  complete, 
they  may  be  more  or  less  laminated,  may  be  quite  structureless, 
or  may  have  a  few  fine  tubes  radiating  from  the  centre  outwards. 
These  tiny  tubes  have  been  probably  produced  by  the  long  fusi- 
form cells. 

It  has  just  been  stated  that  pulp  nodules  are  invariably  solid. 
This  is  not,  however,  quite  correct. 

The  accompanying  photomicrograph  (Fig.  196)  shows  that 
sometimes  a  pulp  nodule  may  contain  a  pulp  chamber  in  its  interior. 
An  example  of  this  occurred  recently  in  the  practice  of  Mr.  Neville 


Fig.  195. — A  pulp  nodule  isolated  from  the  pulp.  Shows  its  central  nuclear 
formation  and  its  concentric  lamination.  Prepared  by  grinding.  Magnified 
50  times.      {From  the  collection  of  G.  W.  Watson.) 


Davis.  Three  teeth  were  removed  from  the  same  mouth,  on  account 
of  excruciating  and  incurable  pain.  The  pulps  contained  the 
largest  nodules  probably  on  record.  One  of  them  measured  in 
width  2.5  mm.  and  in  length  10  mm.  Extending  in  the  central 
axis  of  the  nodule  is  a  canal  filled  with  ordinary  pulp  tissue.  In 
one  section  the  outermost  part  of  the  nodule  consisted  of  fine-tubed 
orthodentine  which  gave  the  growth  a  conical  shape.  Inside  this 
and  filling  up  what  at  one  time  must  have  been  the  pulp  cavity, 
was  a  mass  of  calcareous  material,  with  still  a  small  amount  of 


THE  DEGENERATIONS  OF  THE  DENTAL  PULP 


203 


CM 


Fig.  196. — A  pulp  nodule  in  situ,  containing  an  axial  cavity  filled  with  a 
calcified  mass  resembling  hyperplasic  cementum  or  compact  bone.  Prepared 
by  Weil's  process.  Magnified  12  times,  p.n.  Pulp  nodule;  cm.  Calcified  ma- 
terial occupying  its  interior;  p.  Pulp  tissue;  D.  Dentine;  h.c.  Hyperplasic  cemen- 
tum; J.   Point  of  junction  of  pulp  nodule  with  the  primary  dentine  of  the  tooth. 


204 


THE    DEXTAL    TISSI'TES 


pulp  tissue  remaining.  The  central  hard  mass  contained  a  granular 
matrix,  in  which  were  embedded  great  numbers  of  lacunse  and  inter- 
globular-like  spaces.  Here  and  there  a  few  scattered  dentinal  tubes 
radiating  centripetall}'  were  arranged  in  bundles.     Such  cases  have 


-j  PJN 


Fig.  197. — ^A  pulp  nodule  fused  to  the  parieties  of  a  ptdp  cavity.  Prepared 
by  grmding.  Magnified  15  times,  p.n.  Pulp  nodtile;  d.  Dentine  of  the  tooth. 
(The  section  was  lent  by  J.  F.  Colyer.) 

never  been  described  before:  but  they  are  probably  not  unique. 
(Fig.  196). 

One  or  more  nodules  may  exist  in  the  same  pulp.  They  are 
oftenest  located  in  the  coronal  or  cervical  regions,  but  occasionally 
may  be  found,  as  in  Fig.  igo,  near  the  apical  portion  of  the  root 
canal. 


THE  DEGEXERATI0X5  OF  THE  DENTAL  PULP       205 

Occasionally  a  pulp  nodule  may  be  attached  to  the  wall  of  the 
pulp  ca\'ity.  This  has  been  brought  about  by  new  dentine  from 
the  margin  of  the  pulp  ca\dty,  increasing  and  gradually  encircling 
the  nodule. 

2nd. — Attached  deposits  of  dentine  are  generally  seen  in  the 
coronal  or  cer\-ical  portions  of  the  pulp  (Fig.  197).  They  are 
associated  at  times  with  its  h\-per8eniia  and  inflammation  or,  at 
times,  any  condition,  hke  erosion,  caries,  etc.,  where  there  have 
been  pathological  changes  of  the  dentine. 

WTiere  they  are  due  to  the  latter  and  there  is  a  breach  of  surface, 
they  represent  the  condition  named  by  Salter,  '"dentine  of  repair.'"' 

Generally  speaking,  these  new  masses  of  dentine  include  many 
varieties.  Thus  they  may  differ  but  little  from  normal  flne-tubed 
dentine — the  tubes  perhaps  being  finer  and  less  evenly  distributed. 
They  may  be  almost  structureless;  again  they  may  contain  a  few 
nucleated  cells,  or  spaces  which  closely  resemble  interglobular 
spaces. 

In  aged  teeth,  the  pulp  may  become  partially  or  completely 
calcified.  Long  rods  of  calcific  material  run  longitudinally  through 
its  substance,  and,  in  time,  fuse  and  ultimately  obHterate  all  traces 
of  soft  tissue  (see  Fig.  89). 


CHAPTER  VIII 

THE  PATHOLOGY  OF  THE  PULP  IN  RELATION  TO 
CLINICAL  DENTAL  SURGERY 

Introductory — Carious  lesions — ^Lesions  due  to  Tactile,  Thermal,  Chem- 
ical and  Electrical  stimulations — Referred  Pain  and  Obscure  Reflex 
acts^Receptivity  of  the  Pulp:  Its  Hyperaesthesia  and  Dys'aethesia — ■ 
Phases  of  Degeneration. 

INTRODUCTORY 

The  above  subject  is  of  vast  importance  to  the  Dental  Surgeon, 
but  unfortunately  at  present  only  partially  developed.  The  reason 
why  it  is  only  partially  developed  lies  chiefly  in  the  fact  that  the 
microscopical  technique  associated  with  its  study  is  so  tedious  to 
accomplish,  and  sometimes  so  uncertain  in  its  results,  that  it  does 
not  appeal  generally  to  the  worker  in  dental  histology  in  spite  of 
there  being  ample  clinical  material  and  ample  scope  for  research. 
No  thoughtful  reader  can  for  an  instant  deny  the  immense  impor- 
tance to  the  dental  surgeon  which  attaches  to  the  subject,  especially. 
to  one  who  has  lofty  ethical  ideals  and  who  practices  his  art  in  its 
most  conservative  forms.  All  the  systematic  knowledge  of  diseases 
of  other  organs  of  the  body  which  we  possess — except,  perhaps, 
those  relating  to  myology  and  osteology — the  morbid  conditions 
of  the  blood-vessels,  of  the  nervous  mechanism,  of  the  cellular 
system,  wholly  or  in  part,  simple  or  complicated  as  they  sometimes 
are,  focus  themselves  on  that  minute  structure  in  a  tooth  which 
we  call  the  pulp,  which  is  physiologically  and  in  very  truth  the 
marrow  of  the  tooth. 

THE   DENTAL   PULP   ANALOGOUS    TO  BONE   MARROW — -A  PERFECT 

ORGAN 

There  is  not  so  much  known  about  pathological  conditions  of  the 
marrow  of  bones  generally,  but  one  probably  does  understand  in  a 
measure  some  changes  which  the  marrow  of  a  tooth  has  undergone 
when  subjected  to  local  or  constitutional  disturbances.  And  this 
is  not  at  all  surprising  when  one  begins  to  realize  that  it  is  a  perfect 

206 


THE    PULP    IN    CLINICAL    DENTAL    SURGERY  207 

organ  in  a  way,  with  its  small  arteries,  veins,  capillaries,  and  myelinic 
and  amyelinic  nerve  fibres  and  cells  whose  functions  are  partly 
odontoblastic  in  nature,  and  partly  are  closely  associated  with  the 
sensory  nervous  apparatus— a  perfect  organ  situated  on  the  terminal 
fringe  of  that  comphcated  tangle  of  sentient  fibres,  the  largest 
cranial  nerve,  the  Trigeminus.  It  is  on  this  fact  and  on  all  that  it 
impHes  that  the  importance  of  the  pulp  depends,  and  that  makes 
its  conservation  above  any  other  dental  tissue  of  the  supremest 
moment.  It  would  be  futile  on  the  part  of  the  author  to  marshal 
in  review  the  pathological  conditions  of  which  pulp  may  be  a 
victim.  These  can  be  found  in  preceding  chapters.  This  chapter, 
although  it  does  not  advance  any  novel  or  startling  hypothesis,  is 
designed  to  be  suggestive  rather  than  assertive,  argumentative  rather 
than  dictatorial.  In  other  words,  de  donner  a  penser  a  quelqu'tm,  to 
indicate  possibilities,  and  to  chronicle  one  or  two  sidelights  which 
seem  to  have  some  bearing  on  the  pathology  of  the  organ. 

The  subject  may  have  been  approached  in  two  ways.  On  the 
one  hand,  it  may  have  been  considered  strictly  from  the  point  of 
view  of  the  association  of  certain  signs,  and  subjective  and  objective 
symptoms  and  treatment,  with  the  morbid  conditions  of  the  pulp; 
or  on  the  other  hand,  the  diseases  and  degenerations  of  this  organ 
might  have  been  systematically  and  histologically  described,  and 
linked  in  thought  with  certain  clinical  aspects  of  dental  surgery. 

(I.)  Carious  Lesions 

DIFFICULTIES    IN    ELUCIDATING    CERTAIN    PROBLEMS 

The  author  wishes  it  had  been  possible  for  him  to  have  stated 
clearly  and  satisfactorily  what  happens  to  the  pulp  and  surrounding 
parts  when  obtundent  drugs  have  been  placed  in  a  carious  cavity; 
what  takes  place  when  antiseptic  solutions  are  used,  what  physical, 
chemical,  physiological,  or  pathological  changes  are  induced  when 
the  various  filHng  materials  have  been,  for  a  given  length  of  time, 
brought  into  contact  with  enamel  and  dentine. 

A  perusal  of  the  papers  of  Miller  and  Truman  which  appeared 
in  the  Dental  Cosmos  for  1890  and  1895  respectively,  and  a  search 
through  subsequent  Hterature,  serves  to  show  the  incompleteness 
of  our  knowledge  of  perhaps  the  most  important  and  most  common 
condition  of  things,  viz.,  the  exact  results  which  occur  in  the  daily 
mechanical  and  chemical  treatment  of  diseases  of  the  vitaHzed 
dental  tissues  and  of  the  effects  of  dead  bodies  on  living  substances. 


2o8  THE    DEXTAL    TISSUES 

The  meeting-point  of  the  dead  and  living  is  indeed  a  mystery. 
It  is,  of  course,  admitted  that  many  facts  are  known  about  these 
things.  James  Truman  pubHshed  in  the  Dental  Cosmos  for  January 
1895  a  most  interesting  account  of  his  work  ''On  the  Relative 
Penetrating  Power  of  Coagulants."  In  spite  of  his  writings  being 
punctuated  here  and  there  by  such  words  as  ''possibly,"  ''perhaps," 
'■probablv/'  he  would  seem  to  have  definitely  proved  that  zinc 
chloride  should  not  be  used  as  an  obtundent  of  sensitive  dentine, 
because  ''it  is  exceedingly  dangerous  to  the  life  of  the  pulp,"  though 
he  does  not  precisely  describe  what  causes  this  danger,  and  entirely 
ignores  the  histo-pathological  side  of  the  question.  He  further 
writes:  "In  every  instance,  silver  nitrate  has  proved  deeply  pene- 
trating and  coagulating  with  rapidity  and  certainty  very  nearly  equal 
to  zinc  chloride;'"  but  still  he  adds,  ''The  result  has  not  been  entirely 
satisfactory." 

The  nearest  approach,  however,  to  a  scientific  attempt  to  unravel 
these  knotty  points  was  that  achieved  in  1890,  by  ^Miller,  who, 
nevertheless,  Hmited  his  observations  to  the  comparative  value 
of  antiseptics  used  in  dental  surgery,  making  use  of  pulps  which, 
being  isolated  from  the  mouth,  had  lost  their  natural  living  surround- 
ings. These,  therefore,  at  present,  are  unsolved  problems,  the 
explanations  given  as  to  the  actual  phenomena  which  occur  being 
most  vague. 

DR'ERGEXT    OPIXIOXS    OX    CERTAIX   PROBLEMS 

For  instance,  Black  in  his  ''Operative  Dentistry,"  vol.  i.,  p. 
193,  1908  in  treating  of  the  question  of  curative  effects  of  fillings 
says:  "Fillings  cure  purely  and  simply  by  shutting  out  everything 

from    contact    with    dentine No    systemic    change    is 

produced  as  a  direct  effect." 

Again,  Inglis,  in  the  last  edition  of  Burchard's  excellent  ''Dental 
Pathology  and  Therapeutics,"  writes:  "A  process  of  eburnation 
is  set  up  when  progress  of  caries  is  delayed,  and  in  some  cases 
ceases."  What  is  the  "process  of  eburnation"?  The  writer  tells 
us:  "'The  continued  stimiilation  of  the  ends  of  the  dentinal  fibrillae 
which  are  exposed  in  abrasion  causes  them  either  to  become 
hypersensitive  or  stimulates  them  to  formative  activity.  Tubule 
material  is  built  upon  the  inner  walls  of  the  tubules,  obliterating 
their  lumen.  This  is  the  so-called  tubular  consolidation  or  calci- 
fication (eburnation;." 


THE    PULP    IN    CLINICAL    DENTAL    SURGERY  209 

This  statement  is  in  entire  disagreement  with  that  of  Black,  op. 
cit.  p.  128,  who  says:  "The  suggestion  has  been  made  that  some 
additions  of  calcium  salts  may  be  made  on  the  walls  of  the  dentinal 
tubules,  narrowing  their  calibre.  This  is  plausible,  but  as  yet  no 
sufficient  series  of  measurements  have  been  made  to  determine 
the  facts."  And  again:  "Dentine  or  enamel  once  formed  is  formed 
for  all  time,  it  can  never  be  re-formed,  changed,  or  improved  in  its 
character  or  qualities." 

By  certain  clinical  aspects  of  dental  surgery,  of  which  mention 
was  made  just  now,  is  meant  the  palliative  and  operative  treatment 
of  diseases  of  the  pulp.  This  tissue  with  an  infinite  variety  of 
disease — inflammation  and  its  terminations,  degenerations,  senile 
changes,  and  more  remarkable  reconstructive  potentialities,  offers 
but  few  opportunities  to  the  dental  surgeon  for  the  display  of  his 
surgical  knowledge  and  principles  and  his  skill.  They  may  be 
summarised  as  two  only,  the  problem  being  "  to  cap  or  not  to  cap," 
to  devitalise  or  not  to  devitalise. 

THE   QUESTION    OF   CAPPING    EXPOSURES 

A  superficial  or  deep  ulceration  or  incised  or  punctured  wound 
cannot  be  treated;  it  is  difficult  to  get  rid  of  an  infected  condition, 
or  restore  a  functionless  pulp  to  its  normal  activity,  without  the 
complete  destruction  of  the  organ.  The  anatomical  peculiarities 
of  the  hard  and  soft  parts  are  antagonistic  to  these  things.  If 
the  operation  of  capping  an  exposure  of  the  pulp,  under  the  very 
strictest  aseptic  precautions  is  successful,  it  is  probably  because 
only  non-liquefying  micro-organisms  exist  in  the  dentine  and  in 
the  immediate  neighbourhood  of  the  tooth  which  is  being  treated. 

In  this  connection  it  may  be  recalled  that  Goadby  {Mycology 
of  the  Mouthy  1903)  has  discovered  only  the  Streptococcus  pyogenes 
(viridans)  and  the  Bacillus  necrodentalis,  which  are  liquefying 
organisms,  in  the  deep  layers  of  carious  dentine. 

In  I  goo,  in  Paris,  the  author  {Trans.  Third  International  Dental 
Congress)  ventured  to  emphasise  the  fact  that  capping  was,  as  a  rou- 
tine method  of  practice,  always  a  failure.  It  seems  to  him,  after  a 
riper  experience,  that  generally  the  operation  is  not  a  success  on 
account  of  the  prevalence  and  presence  of  these  facultative  (obli- 
gatory) aerobes,  which,  according  to  Goadby,  are  capable  of  ob- 
taining oxygen  from  gelatine,  which  is  the  end-product  of  collagen. 

14 


2IO 


THE    DENTAL    TISSUES 


THE    PHYSIOLOGICAL    RESISTANCE    OF  THE  HEALTHY  PULP 

But  this  is  not  all.  There  is  another  factor  which  is  probably 
of  greater  importance  than  the  presence  of  these  micro-organisms; 
this  is  the  physiological  resistance  of  the  pulp.  It  would  seem  that 
when  the  operation  of  capping  is  unattended  by  pain  or  by  death  of 
the  pulp — no  matter  how  long  delayed  after  the  actual  treatment — 


p  D 


Fig.  198. — Logitudinal  section  of  canine  with  pulp  in  situ.  Enamel  was 
hypoplasia,  and  subsequently,  with  the  dentine,  became  carious.  There  are 
no  micro-organisms  in  the  adventitious  dentine,  p.d.  Primary  dentine;  p.  Pulp; 
A.D.  Adventitious  dentine.      Magnified  12  times. 

it  is  due  to  the  physiological  resistance  not  only  on  the  part  of  the 
pulp  itself,  but  also  on  the  part  of  the  adventitious  dentine  which 
has  been  deposited  on  its  surface.  The  author  has  failed  in  his  at- 
tempts to  stain  bacteria  in  the  pulp  and  adventitious  dentine  in  some 
carious  teeth  which  presented  a  hypoplasic  condition  of  the  enamel. 
This  leads  him  to  suppose  that  if  this  adventitious  dentine  is  produced 
early  by  an  energetic  pulp,  and  if  the  caries  proceeds  at  a  slow 


THE    PULP    IN    CLINICAL   DENTAL    SURGERY 


211 


uniform  rate,  the  pulp  will  not  become  infected  and  the  case  would 
be  suitable  for  capping  an  exposure,  if  one  should  by  any  chance 
be  made,  either  idiopathically  or  traumatically  or  pathologically. 

Miller  considered  that  there  is  in  the  thin  free  margin  of  enamel 
a  certain  amount  of  physiological  resistance,  as  also  in  the  trans- 
lucent zone  of  carious  dentine. 

It  is  probable,  nay  certain,  that  a  large  amount  of  physiological 
resistance  resides  in  the  pulp  also,  as  witness  the  unvarying  fre- 
quency with  which  it  lays  down  adventitious  dentine.     And  if  a 


PD 


J       ( 
i     ■ 

■   V 


LL 


Fig.  199. — Areolar  adventitious  dentine — a  most  suitable  nidus  for  the  growth 
and  development  of  the  micro-organisms  of  caries.  Rapidly  formed  as  a  pro- 
tection of  the  pulp.     P.D.  Primary  dentine.      Magnified  200  times. 

perfect  capping  has  been  performed  and  facultative  micro-organisms 
are  absent  or  few  in  number,  and  the  pulp  always  retains  its  high 
degree  of  physiological  resistance,  the  results  will  be  entirely 
satisfactory. 

Therefore,  given  a  healthy  pulp,  the  success  of  this  operation 
would  appear  to  depend  on  three  conditions:  (i)  A  sUght  injury, 
(ii)  Absence  of  facultative  aerobes,  (iii)  Well-maintained  physio- 
logical resistance  of  the  pulp,  and  of  its  adventitious  dentine. 

Conversely,  therefore,  anything  which  destroys,  or  reduces,  or 
abolishes  this  physiological  reaction,  such  as  prolonged  mental 
anxiety,  chronic  wasting  diseases,  often  repeated  traumatisms  of 
the  hard  parts,  frequent  and  varied  thermal  stimulations,  will  in 


212 


THE    DENTAL    TISSUES 


the  end,  in  spite  of  the  aseptic  care  of  the  operator,  tend  to  bring 
about  disaster,  and  the  pulp  will  die. 


REGIONAL    HYPEREMIA 


Dental  caries,  when  acute,  is  accompanied  in  its  early  stages 
by  a  regional  hyperaemia  which  according  to  the  part  attacked — 
that  is,  that  which  is  nearest  to  the  breach  of  surface-^-is  either 
coronal,  cornual,  cervical,  or  radicular.     Sections  of  teeth  extracted 


^>-' 


Fig.  200. — Longitudinal  section  through  a  cusp  of  a  molar  showing  signs  of 
"arrested"  caries.  Surface  of  enamel  and  dentine  (where  exposed)  blackish 
in  color,  e.  Enamel;  d.  Dentine;  c.  Caries  making  breach  of  surface  of  enamel 
prior  or  subsequent  to  the  general  arrest  of  the  process.  "White  spot "  absent; 
enamel  tissue  fully  stained.      Magnified  45  times. 

during  a  paroxysm  of  odontalgia  reveal  this  quite  clearly,  but 
chronic  caries  does  not  necessarily  produce  it.  Coronal  regional 
hyperaemia  may  exist  to  a  slight  degree  in  such  caries,  but  when  the 
physiological  resistance  of  the  pulp  is  fully  restored  and  permanently 
established,  not  only  does  this  hyperaemia  undergo  resolution,  but 


THE    PULP    IN    CLINICAL   DENTAL    SURGERY  213 

the  contents  of  the  dentinal  tubes  claim  their  share  in  the  physio- 
logical resistance,  and  arrested  caries  results,  often  the  whole  phe- 
nomena of  decay  and  arrest  proceeding  without  any  pain. 

I      ARRESTED   CARIES 

One  would  have  thought  that  arrested  caries  would  have  been 
associated  with  deposits  of  secondary  and  adventitious  dentine  on 
the  pulp  surface.  This  is  not  necessarily  so.  Specimens  of  true  ar- 
rested caries  are  not  easy  to  obtain,  but  those  that  have  been  pre- 
pared show  no  sign  of  this,  nor  pathological  conditions  of  the  pulp. 
If  specimens  have  been  prepared  by  the  Koch-Weil  method,  even 
before  immersion  in  the  graduated  alcoholic  solutions,  the  dentine 
is  extremely  hard  and  resistant  to  a  fine  saw,  such  as  an  American 
No.  4.  What  enamel  remains  on  the  surface  is  also  exceedingly 
dense  and  difficult  to  cut.  Curiously  enough,  however,  and  for 
what  reason  it  is  at  present  impossible  to  determine,  the  enamel 
rods  become  stained  throughout  their  length  by  means  of  the  Gre- 
nacher's  borax  carmine  which  is  used  in  conjunction  with  this  proc- 
ess (Fig.  200).  The  transverse  striae  are  more  marked  than  natu- 
ral, and  the  tissue  has  the  appearance  of  having  been  washed  in 
a  weak  acid  solution.  This  staining  of  the  enamel  may  not  occur 
universally;  the  calcification  of  the  teeth  varies  considerably  even 
in  the  same  mouth.  Still  it  is  evident  that  but  little  clinical  sig- 
nificance can  lie  in  this  fact,  although  it  is  interesting  from  the  his- 
tological point  of  view.    1 

SOME    SENILE    CHANGES 

As  age  advances,  the  pulp  cavity  is  not  encroached  upon  to  any 
appreciable  extent  by  new  deposits  of  dentine  as  a  normal  event. 
The  author's  observations  do  not  accord  with  Tomes,  who  remarks 
in  the  1906  edition  of  "A  System  of  Dental  Surgery,"  page  416, 
"The  area  of  the  pulp  cavity  becomes  gradually  diminished  by  the 
slow  addition  of  dentine  to  that  which  was  formed  when  the  tooth 
was  in  a  state  of  active  growth;"  nor  with  those  of  Dr.  Loos,  who, 
inSchefsHandbuchfur  Zahnheilkunde,  1908,  states  that "  There  must 
be  mentioned  a  general,  physiological,  senile  new  formation  of  den- 
tine," and  continues:  "With  the  entire  developmentof  the  teeth,  nor- 
mal dentine  formation  does  not  stop,  but  continues  slowly  up  to  the 
greatest  period  of  age.     A  proof  of  this  is  the  fact  that  the  pulp 


214 


THE    DEXTAL    TISSUES 


cavity  in  advanced  age  is  found  to  be  smaller  than  in  earlier  years — 
indeed,  it  may  entirely  disappear  and  this  physiological  new  for- 
mation of  dentine  produces  most  diffuse  uniform  thickening  of  the 
dentine  wall.  It  appears,  however,  that  this  dentine  formation  does 
not  take  place  uniformly  over  the  whole  wall  of  the  pulp  cavity. 
The  root-canals  in  advanced  age  are  mostly  found  narrowed;  but 
frequentlv  on  the  wall  of  the  pulp  chamber  only  certain  places  are 
distinctlv  altered,  viz. :  those  which  border  on  the  pulp  chamber  in  a 
vertical  direction.     As  the  size  and  form  of  the  pulp  cavity  are  sub- 


A  D 


Fig.  201. — ^Longitudinal  section  (mesio-distal  diameter)  of  lower  incisor  of 
patient  aged  seventy-one.  Pulp  chamber  filled  with  debris  and  detritus  by 
grinding.  Small  amount  of  adventitious  dentine — marked  attrition,  p.d. 
Primary  dentine;  ad.  Adventitious  dentine.      Magnified  12  times. 

ject  to  manifold  individual  variations,  it  is  often  very  difficult  to 
find  out  whether  we  have  to  do  with  normal  or  with  altered  condi- 
tions. Histologically  this  dentine  does  not  exhibit  any  noteworthy 
differences  from  the  normal,  and  it  can  scarcely  be  distinguished  from 
substituted  dentine  or  'odontheles"  (pulp  nodules)." 

If  this  is  a  normal  physiological  process  on  the  part  of  the  pulp, 
one  would  expect  to  find  it  universally  in  all  senile  teeth;  but  it  is 
not  so.  The  accompanying  figure  for  instance,  is  a  case  in  point, 
where  the  diameter  of  the  pulp  chamber  measures  3  mm.  (Fig.  201). 
The  historv  of  the  tooth  was  as  follows:  ''Male,  aged  seventy-one. 


THE    PULP    IN    CLINICAL   DENTAL    SURGERY 


215 


No  inflammation  of  pulp,  slight  amount  of  tartar,  tooth  loose,  not 
isolated  in  position,  alveolar  process  absorbed  and  walls  of  sockets 
thinned,  'pyorrhea'  present  very  markedly." 

It  is  quite  impossible  to  understand  how  calcification  of  the 
dentinal  tubules  can  occur  and  how  the  pulp  chamber  can  become 
lessened  in  size,  except  by  the  production  of  new  adventitious  den- 
tine.    Of  course  odontoblasts  are  still  present  up  to  the  end  of  the 


PD 


C  P 


Fig.   202. — Longitudinal    section    of  a   senile   tooth,      e.   Enamel;  p.d.  Primary 
dentine,      c.p.   Calcified  pulp.      Magnified  12  times. 


life  of  the  pulp,  but  they  are  not  functional  after  the  fiftieth  or 
sixtieth  year.  When  the  process  of  dentinification  has  ceased,  and 
fresh  secondary  dentine  is  deposited,  the  microscope  usually  exhibits 
very  clearly  the  line  of  demarcation  between  young  and  old  tissue. 
The  idea  which  has  been  current  for  generations  probably  arose  in 
the  attempt  to  account  for  the  discrepancies  in  the  size  of  the 
calibre  of  the  dentinal  tubules  at  their  centripetal  and  centrifugal 
extremities. 


2l6  THE    DENTAL    TISSUES 


SYSTEMATIC    DENTAL   HISTORIES 


At  this  juncture  the  writer  must  digress  sHghtly  from  his  subject 
in  order  to  draw  attention  to  the  need  for  and  the  methods  of  system- 
atically obtaining  reports  of  teeth  which  should  be  of  scientific 
value  when  research  work  is  being  done.  He  refers  to  the  individual 
''histories"  of  teeth.  It  is  important  that  the  investigator  should 
learn  thoroughly  all  he  can  about  the  objects  he  studies,  and  so  it 
seems  imperative  that  with  regard  to  teeth  which  are  about  to  be 
examined  the  following  points  should  be  ascertained:  (i)  Age  of 
the  patient.  (2)  Sex.  (3)  Denomination  of  the  tooth.  (4)  Ob- 
vious disease  of  the  pulp  or  periodontal  membrane.  (5)  Presence 
of  "pyorrhea  alveolaris."  (6)  Position  of  the  tooth  or  teeth  in 
regard  to  the  dental  arch.  (7)  Conditions  of  the  socket  at  the  time 
of  extraction.  (8)  Presence  or  absence  of  tartar.  (9)  Presence  or 
absence  of  any  obvious  lesions  of  the  hard  parts,  such  as  attrition^ 
abrasion,  or  erosion. 

The  Age  of  the  patient  is  useful  as  a  general  guide  as  to  what  to 
expect.  One  need  not  dwell  on  the  importance  of  this  in  the  young. 
Apart  from  the  question  of  age  in  treating  the  irregularities  in 
position  of  the  teeth,  it  is  equally  essential  to  ascertain  the  age  of 
the  patient  in  order  to  gage  somew^hat  the  conditions  of  the  pulp  or 
root  membrane.  Thus  one  knows  that  the  apical  foramen  in  the 
permanent  canine  is  closed  shortly  after  the  tooth  has  erupted.^  One 
knows  that  the  pulps  of  elderly  people  become  less  sensitive  as  years 
pass  by.  One  knows  that  there  are  three  cornua  to  the  pulp  of  the 
permanent  first  incisor  up  to  the  fifteenth  year,  w^hen  they  disappear; 
and  so  on.  But  age  does  not  always  prove  a  reliable  guide,  for,  as 
has  been  already  shown,  very  frequently  the  pulps  of  children's 
deciduous  and  permanent  teeth  may  exhibit  senile  and  other  de- 
generative changes. 

Sex. — One  cannot  recognize  with  facility  the  difference,  either 
macroscopically  or  microscopically,  between  the  teeth  of  a  male  or 
a  female  patient.     Of  course  this  degree  of  variation  is  nothing  hke 

1  The  approximate  dates  of  "closure"'  of  the  apical  foramina  of  the  permanent 
teeth  may  be  given  as  follows:  A.  The  ^Maxillary  series — First  incisor,  nth  year; 
Second  incisor,  nth  year;  Canine,  13th  year;  First  premolar,  12th  j^ear; 
Second  premolar,  12th  j^ear;  First  molar.  12th  year;  Second  molar,  15th  3'ear; 
Third  molar,  19th  year.  B.  The  Mandibular  series — First  incisor,  loth  year; 
Second  incisor,  nth  year;  Canine,  13th  year;  First  premolar,  12th  year;  Second 
premolar,  12th  3'ear;  First  molar,  nth  \-ear;  Second  molar,  i6th  year;  Third 
molar,  21st  year. 


THE    PULP    IN    CLINICAL   DENTAL    SURGERY  217 

SO  great  as  between  the  hair,  or  brain,  etc.,  of  the  two  sexes.  The 
curvatures  of  the  enamel  rods  are  apparently  the  same;  the  structure 
of  the  two  pulps  is  apparently  identical.  But  the  author  believes 
that  there  is  a  dissimilarity  between  them  in  the  size,  the  structure, 
and  the  chemical  and  functional  characteristics  of  the  teeth. 

Regarding  the  first,  Amoedo  (L^Art  Dentaire  en  Medecin  Legale, 
1898)  records  in  a  tabulated  form  some  measurements  made  by 
Mela  between  the  size  in  transverse  diameter  of  the  first  and  second 
incisors  of  man  and  woman.  The  figures  show  that  the  mean  dif- 
ference between  the  dimensions  in  a  mesio-distal  direction  of  the 
first  maxillary  incisors  of  the  two  sexes  is  0.627  mm.;  of  the  maxil- 
lary second  incisors  0.159  "^™^-  The  mean  measurements  between 
the  maximum  diameters  of  the  first  and  second  incisors  was  2.25 
mm.  in  man,  and  1.89  mm.  in  woman,  a  difference  of  0.38  mm.  The 
maximum  diameter  of  man's  first  incisors  gave  a  maximum  of  11  mm. 
and  a  minimum  of  7.5  mm.,  that  of  the  same  teeth  of  woman  giving 
a  maximum  of  9.8  mm.  and  a  minimum  of  7.1  mm.  "La  difference 
sexuelle  entre  les  deux  extremes  des  incisives  centrales  superieures," 
he  writes,  "est  de  1.3  mm.  a  I'avantage  du  sexe  masculin.  .  . 
La  difference  sexuelle  entre  les  deux  extremes  des  incisives  laterales 
superieures  est  de  5  mm.  en  faveur  du  sexe  masculin." 

Regarding  the  last,  the  teeth  of  women  would  appear  to  be  less 
subject  to  attrition  or  abrasion;  they  cannot  be  influenced  by  the 
same  amount  of  muscular  power  as  the  former,  though  the  food  is 
more  or  less  identical.  The  respective  dental  and  muscular  dynamics 
and  potentialities  of  mastication  are  distinct,  and  if  tested  by  means 
of  a  dynamometer  would  probably  be  found  to  differ. 

Comparative  anatomy  teaches  that  the  teeth  of  the  female  vary 
in  development,  in  size,  and  sometimes  in  function,  from  those  of 
the  male;  instances  need  not  be  given.  We  also  learn  that  if  but  a 
slight  amount  of  work  has  to  be  accomplished,  tooth  structure  is 
profoundly  modified.  Thus  the  Edentata  have  no  enamel,  simply 
because  their  food  is  of  so  soft  a  character  as  to  involve  practically 
the  abolition  of  the  function  of  mastication.  Again,  the  enamel  of 
the  Manatee  is  arranged  in  rods  which  run  straight  courses;  on  the 
other  hand,  that  of  the  rodents,  particularly  the  beaver,  presents  a 
most  complicated  pattern.  The  former  does  not  require  for  eating 
aquatic  plants  a  dense  structure  such  as  the  latter,  whose  teeth  are 
used  for  gnawing  and  chiseling  the  barks  and  trunks  of  trees.  Hence, 
at  first  sight,  though  it  seems  strange  to  suppose  this  x  difference 
between  male  and  female  teeth,  there  is  some  support  for  the  idea. 


2l8  THE    DENTAL    TISSUES 

At  all  events,  the  author  thinks  that  there  is  certainly  some  ground 
for  the  belief  that  the  pulps  of  the  teeth  of  women  may  and  often 
do  undergo  unique  vascular  disturbances  at  certain  periods  of  their 
lives;  and  this  fact  alone  would  constitute  a  fundamental  difference 
between  the  two. 

The  Denomination  of  the  tooth  is  important.  The  enamel  of 
incisors  is  less  complex  in  pattern  than  that  of  the  molars.  From  the 
chemical  point  of  view,  also,  there  is  a  remarkable  difference.  Gass- 
mann,  in  the  Zeitschrift  Jilr  Physiologische  Chemie,  1908,  discovered 
as  a  result  of  his  investigations  that  human  canines  contain  29.78 
per  cent,  of  calcium  salts,  third  molars  31.65;  of  water  combined 
with  the  organic  matters,  8.09  in  the  former  and  6.91  in  the  latter. 
Pulps  appear  to  be  histologically  identical,  but  most  probably  there 
is  here  again  a  dissimilarity  which  one  is  not  clever  enough  at  present 
to  detect  and  acknowledge. 

In  other  words,  just  as  there  are  no  two  persons  exactly  alike, 
no  two  animals,  no  two  birds,  no  two  plants,  no  two  blades  of  grass, 
so  there  are  no  two  teeth  precisely  and  in  every  minute  particular  the 
same. 

With  regard  to  the  other  points  which  have  been  outlined,  which 
should  be  given  in  the  histories  of  cases,  one  need  not  dwell  on  each 
in  detail.  One  will  merely  add  that  a  tooth  which  is  isolated  in 
position,  from  removal  of  anterior  and  posterior  neighbours,  is  more 
likely  to  undergo  morbid  changes  than  one  which  is  part  of  an  un- 
broken series,  owing  to  the  undue  strain  or  shock  of  mastication; 
that  a  loose  tooth  is  a  degenerate  or  degenerating  organ,  and  that  the 
presence  or  absence  of  calculus  is  of  great  importance,  inasmuch  as 
the  greater  the  amount  of  tartar  which  incrusts  the  surfaces,  and  the 
longer  it  remains  in  situ,  the  less  functional  the  tooth  and  therefore 
the  more  liable  to  become  impaired  the  pulp. 

In  addition  to  this,  the  naked-eye  examination  of  the  specimen 
must  be  described,  viz. :  the  amount  of  tartar  (if  present) ;  its  position 
on  the  root  or  roots;  its  distance  from  the  cervical  margin;  its  nature; 
the  translucence  or  otherwise  of  the  apical  region  of  the  root;  the 
deflections  or  normal  appearances  of  the  root;  the  amount  of  abrasion 
of  the  crown,  etc.;  in  short,  all  the  abnormal  characteristics  of  the 
object  under  consideration  as  far  as  the  macroscopical  appearances 
are  concerned. 


THE    PULP   IN    CLINICAL   DENTAL    SURGERY 


219 


(II.)  Non-Carious  Lesions 

(a)  lesions  due  to  tactile,  thermal,  chemical,  and      ; 
electrical  stimulations 

(i)  Tactile  impressions  which  set  up  pain  are,  as  is  well  known, 
those  in  relationship  with  the  surfaces  of  the  cervical  margins  of  the 
teeth.     No  lesion  may  exist  to  the  naked  eye;  but  there  is  a  micro- 


FiG.  203. — Cementum,  showing  its  hyaline  character  and  absence  of  lacunae, 
the  three  dark  masses  being  foreign  bodies  on  the  surface  of  the  tissue,  d. 
Dentine;  c.  Cementum;  p.m.  Periodontal  membrane;  a. p.  Alveolar  process. 
Magnified  250  times. 

scopical  one.  These  hypersensitive  surfaces  very  frequently,  indeed, 
develop  into  acutely  esthetic  cavities.  Whence  comes  the  pain?  and 
what  is  found  on  histological  examination?  A  tiny  strip  of  dentine 
uncovered  by  the  other  hard  tissues.  The  anatomical  relation- 
ships of  the  hard  tissues  at  the  necks  of  teeth  are  as  follow:  (a) 
Enamel  overlaps  the  cementum  in  about  .5  per  cent,  of  cases,  {h) 
Cementum  overlaps  the  enamel  in  60  to  65  per  cent,  of  cases,   {c)  The 


220  THE    DENTAL    TISSUES 

two  tissues  meet  bout  a  bout  in  30  per  cent,  of  cases,  (d)  Finally, 
they  fail  to  meet  at  all,  and  leave  the  peripheral  surface  of  the  dentine 
exposed,  in  5  to  10  per  cent,  of  cases. 

Thus  normally,  it  would  appear,  that  the  two  tissues  are  in 
absolute  contact,  and  both  lie  in  the  same  plane  without  any 
involution  whatever  (see  Chap.  Ill,  Vol.  i). 

Now,  enamel  being  outside  the  pale  of  nutrition,  and  once  formed 
always  formed,  and  cementum  itself  being  insensitive,  it  is  clear 
that  the  dentinal  tubules  are  actually  exposed  at  their  distal  ex- 
tremities, and  their  contents  are  irritated  by  the  pressure  or  presence 
or  friction  of  a  foreign  body  in  that  region.  Enamel  is  nerveless, 
and  cementum  in  normal  conditions  does  not  contain  any  elements 
of  a  nervous  or  protoplasmic  character  in  sufhcient  amount  to  induce 
pain  in  suitable  circumstances.  No  doubt  prolonged  irritation 
might  lead  to  exalted  sensibility  on  the  part  of  the  pulp,  and  if 
decalcili cation  of  the  thin  edges  of  the  enamel  and  cementum  takes 
place,  with  loss  of  substance,  an  erosion  cavity  is  produced. 

(2)  Thermal  sensations  are  easily  explained,  owing  to  their  being 
due  to  a  raised  or  lowered  temperature  of  the  pulp  through  conduc- 
tion on  the  part  of  the  enamel — a  state  of  things  which  the  pulp 
immediately  recognizes,  by  means  of  the  dentinal  fibrils.  It  does 
not  always  happen  that  a  pulp  is  painful  when  icy-cold  or  hot  water 
is  placed  on  the  enamel.  When  it  is,  however,  it  is  either  hyperaes- 
thetic,  or  perhaps  more  correctly,  h^-peralgesic,  and  is  more  readily 
affected  by  outside  influences  than  it  should  be,  or  the  sensorium 
is  more  appreciative  than  natural  of  the  impressions  conveyed  to 
it  from  the  pulp. 

Occasion  arises  sometimes  when  a  devitalised  tooth  whose  pulp 
has  been  removed  gives  the  impression  to  the  patient  by  pain  that 
it  is  still  present  and  alive.  The  exhaustion  of  air  around  the  neck  of 
the  tooth — that  is,  an  alteration  in  or  lowering  of  the  local  tempera- 
ture on  the  part  of  the  patient — gives  rise  to  pain.  On  examination 
it  may  be  found  that  the  interdental  gum  may  have  been  inadver- 
tently removed  while  operating  on  the  adjacent  tissues,  and  the 
free  edge  of  the  periodontal  membrane  nearly  exposed.  It  is  there- 
fore probable  that  the  root  membrane  transmits  the  sensations  of 
pain  to  the  brain,  which  interprets  it  as  that  coming  from  the  pulp. 
With  regard  to  those  cases  of  a  root  or  portion  of  a  root  which,  having 
been  denuded  of  its  alveolar  socket  and  mucous  membrane,  such  as 
is  frequently  observed  in  connection  with  the  palatal  roots  of 
maxiUary   molars,    is   very    sensitive    to  thermal    changes,  and  is 


THE    PULP    IN    CLINICAL   DENTAL    SURGERY 


221 


rendered  insensitive  by  means  of  the  application  of  silver  nitrate,  the 
author  is  not  prepared  to  state  what  really  occurs.  Cementum  is 
incapable  per  se  of  transmitting  sensations;  and  "the  living  chain  of 
protoplasm"  which  Bodecker  so  deftly  described  as  passing  from  the 
dentinal  fibrils  through  the  granular  layer  of  Tomes  to  the  lacunae 
and  canaliculi  of  the  cementum,  and  so  on  to  the  nervous  bundles  of 
the  periosteum,  is  a  myth.     For  a  solution  of  silver  nitrate  cannot 


'{Jr.  i  «!' 


Fig.    204. — Same   as   preceding,    but  differently  illuminated,   to  show  granular 
character  of  cementum. 


soak  through  cementum  whose  free  layers  are  almost  homogeneous 
in  character  and  hyaline  in  structure  (Figs.  203  and  204). 

If  a  pulp  is  frequently  painful  when  hot  substances  and  fluids  are 
taken  into  the  mouth,  it  indicates  that,  though  there  may  be  no 
apparent  lesion,  it  is  certainly  on  the  "down  grade." 

(3)  Chemical  Stimuli: — The  appHcation  of  lukewarm  mineral  acids 
or  alkalis  to  an  unbroken  surface  of  the  teeth  gives  rise  to  no  pain  in 
the  pulp. 

(4J  Electrical  impulses,  however,  are  full  of  interest.     "Electric 


222  THE    DEXTAL    TISSUES 

cells  are  frequently  formed  in  the  mouth,  metalHc  poles  being  present 
and  an  electrolyte  intervening.  The  greater  the  electro-positive 
or  electro-negative  the  metal,  the  greater  the  electro-motive  force. 
Now,  in  the  electrolytic  scale,  gold  is  nearly  the  most  electro-negative 
of  all  metals  placed  in  the  mouth;  while  aluminium  is  the  most  electro- 
positive. If,  therefore,  two  metals  of  different  electromotive  force 
come  into  contact  or  almost  into  contact,  and  the  saliva  is  ionized 
to  such  an  extent  as  to  be  efficiently  electrolytic,  the  cathions,  or  — 
ions,  will  move  toward  the  +  pole  or  more  electropositive  side,  while 
the  anions,  or  +  ions,  will  move  toward  the  —  pole,  and  a  certain 
amount  of  electricity  will  be  evolved. 

''  This  action  maybe  carried  to  a  greater  degree  than  is  usual  in  the 
mouth.  Clinically  this  force  becomes  more  manifested,  at  times, 
under  certain  conditions,  in  a  disastrous  manner.  Thus  a  i6-carat 
gold  band  which  is  used  for  supporting  a  denture,  if  attached  to  a 
molar  tooth,  for  instance,  which  contains  a  large  amalgam  filling, 
may  in  these  cases  become  so  electrically  affected  as  to  break,  on 
account  of  the  molecular  changes  set  up  by  the  current,  and  the 
filling  similarly  to  become  disintegrated  and  fall  out. 

"  Mere  contact  of  a  metal  with  enamel  or  dentine  is  not  appreciated 
by  the  pulp.  It  is  when  two  dissimilar  metals  are  brought  into 
contact,  separated  only  by  a  thin  film  of  saliva,  which  acts  as  the 
electrolyte,  and  the  circuit  is  completed,  that  voltaic  currents  are 
set  up — as  for  instance  when  the  metal  ring  of  a  small  mirror  touches 
the  surface  of  a  gold  or  an  amalgam  filling.  This,  of  course,  con- 
stantly takes  place  during  operations,  and  is  as  a  rule  unnoticed  by 
the  patient,  on  account  of  its  extremely  light  character;  but  at  times 
the  pulp,  stimulated  by  the  electrical  action,  responds  by  a  sudden 
spasm  of  acute  odontalgic  pain."  ("An  Introduction  to  Dental 
Anatomy  and  Physiology"  1913.)  Is  the  pulp  normal  in  these  latter 
fairly  rare  cases?  Probably  not — it  is  beginning  to  undergo  morbid 
changes;  for  the  phenomenon  may  be  observed,  as  far  as  chnical 
experience  goes,  equally  beneath  large  as  well  as  less  bulky  fillings. 
The  pulp  is  not  hyperaemic;  it  is  hypersensitive,  or  particularly 
"receptive," — owing,  no  doubt,  to  an  exalted  condition  of  the  cerebro- 
spinal nervous  system  which  happens  to  be  synchronous  with  the 
electrical  phenomena.  Tests  as  to  the  acidity  or  otherwise  of  the 
saliva  are  unattended  by  success.  Here,  of  course,  mere  contact 
with  the  filling  alone  induces  no  response;  the  circuit  must  be  com- 
pleted, either  by  simultaneously  touching  filling  and  tongue  or 
filling  and  buccal  mucous  membrane. 


THE    PULP    IN    CLINICAL   DENTAL    SURGERY  223 

It  is  interesting  to  note  that  the  same  degree  or  kind  of  reaction  of 
the  saliva  may  not  obtain  simultaneously  in  the  same  mouth.  Thus 
some  portions  of  the  gums  or  buccal  mucous  membrane  may  show,  at 
the  same  moment,  an  acid,  an  alkahne,  and  a  neutral  reaction  to 
litmus  paper. 

(b)  referred  pain  and  obscure  reflex  acts 

Entirely  different  from  these  local  manifestations  are  those  nerve 
pains  set  up  in  apparently  sound  teeth  on  holding  lukewarm  saccha- 
rine substances  in  the  mouth. 

A  particularly  sweet  body,  for  instance,  will  at  times,  when  the 
functions  of  the  central  nervous  mechanism  are  exalted,  give  rise  to 
intensely  acute  pain  which  may  last  an  appreciable  length  of  time 
and  then  passes  slowly  away.  This  is  no  mere  gustatory  hallucina- 
tion, no  co-ordinated  association  of  ideas,  but  a  physiological  fact. 
Here  is  a  reflex  act.  It  is  impossible  for  sugary  solutions  per  se  to 
so  rapidly  attack  enamel  or  cementum  or  even  exposed  dentine  as 
to  induce  these  pains.  The  length  of  time  required  for  the  paroxysm 
to  make  itself  felt  after  the  appHcation  of  the  stimulus  is  about  0.05 
to  0.06  of  a  second.  It  is  not  through  the  hard  tissues  that  the  im- 
pulse passes,  it  is  through  the  nerve  supply  of  the  pulp.  The 
afferent  nerves  are  those  sensory  branches  of  the  Fifth  which  supply 
the  oral  mucous  membrane,  and  the  gustatory  and  glosso-pharyn- 
geal,  with  possibly  the  Chorda  tympani;  and  it  is  the  act  of  placing 
the  saccharine-bearing  material  on  the  tongue  and  inside  of  the  cheek 
that  brings  about  the  reflex  act.  This,  too,  only  occurs  at  times, 
when  probably  the  sensorium  is  especially  liable  to  receive  and  trans- 
mit slight  impulses  to  teeth,  the  pulps  of  which,  while  not  degenerated 
are  certainly  not  entirely  normal. 

There  are  many  examples  of  the  pulps  of  teeth  causing  pain  when 
there  is  no  obvious  lesion.  Occasionally  the  eating  of  very  sweet 
or  sour  bodies  will  set  up  excruciating  synalgia  in  sound  teeth. 
Through  the  glosso-pharyngeal  and  the  Chorda  tympani  nerve  sen- 
sations are  felt  by  the  brain,  which  as  in  the  case  of  the  amputated 
foot  makes  an  error  of  judgment  as  to  the  position  of  the  stimulus. 
In  its  essence  it  is  akin  to  mysophobia  and  certain  other  systemic 
morbid  emotivities. 

Reverting  for  a  moment  to  this  question  as  an  aid  to  the  proper 
understanding  of  this  reflex  act,  we  know  that  mysophobia,  or  the 
fear  of  improper  or  inapposite  contacts  is  not  confined  to  manifes- 


2  24  THE    DENTAL    TISSUES 

tations  in  the  form  of  a  natural  aversion  to  touching  disagreeable 
bodies,  or  those  capable  of  undergoing  decomposition.  Many  people 
cannot  bear  to  perceive,  by  the  sense  of  touch,  the  surface  of  fab- 
rics such  as  velvets  or  silks,  or  the  external  parts  of  the  skins  of 
fruits  such  as  peaches.  There  may  arise  in  the  minds  of  some, 
fear  of  contact  with  metallic  objects,  such  as  copper,  pins,  and  nee- 
dles, or,  according  to  MorselH,  pieces  of  glass.  It  is  possible  that 
derangements  of  the  tactile  digital  sensibility  are  partly  the  cause;  for 
Marce  has  described  a  case  in  which,  through  a  fear  of  seeing  pins 
or  needles  adhering  to  the  fingers,  complete  insensibility  of  the  skin 
of  the  hand  was  produced.  Among  other  illustrations  of  systemic 
morbid  emotivity.  Morel,  quoted  by  Dr.  Charles  Fere  in  his  "La 
Pathologie  des  Emotions,"  1899,  cites  the  following:  King  James 
II  of  England  trembled  at  the  sight  of  a  naked  sword;  Erasmus 
suffered  from  febrile  fits  on  seeing  a  plate  of  lentils;  Scaliger  was 
seized  with  nervous  tremors  at  the  sight  of  a  carafe  of  water;  Bacon 
experienced  the  state  of  syncope  during  every  lunar  eclipse. 

''setting    THE    TEETH    ON    EDGE" 

The  complex  series  of  phenomena  constituting  that  anomaly  of 
sensibility  popularly  spoken  of  as  "setting  the  teeth  on  edge" 
may  perhaps  be  placed  in  the  same  category  as  the  preceding 
illustrations,  for,  in  this  case,  it  is  partly  the  outcome  of  an  innate 
antipathy  on  the  part  of  the  individual.  It  is  something  more  than 
a  mere  reflex  act,  inasmuch  as  it  is  accompanied  and  complicated 
by  a  mentahty  which  is  the  effect  of  the  workings  of  a  higher  con- 
scious cerebration.  This  syncinesia,  among  others  studied  by  John 
Hunter,  Miiller,  and  Gubler,  which  is  purely  physiological,  or  perhaps 
borders  on  the  abnormal,  may  be  caused  partly  by  the  action  of 
the  auditory  nerves,  and  partly  by  the  gumaisthenic  or  somaisthenic 
perceptions  of  the  person. 

Gumaisthenic  Perceptions. — The  phenomenon  was  known  to  the 
Prophets  of  old  whose  words,  recorded  in  the  Bible,  are  as  follow: 

Prov.  X,  26:  As  vinegar  to  the  teeth,  and  as  smoke  to  the  eyes,  so  is  the 
sluggard  to  them  that  send  him. 

Ezek.  xviii,  2 :  What  mean  ye,  that  ye  use  this  proverb  concerning  the  land 
of  Israel,  saying  "The  fathers  have  eaten  sour  grapes,  and  the  children's 
teeth  are  set  on  edge  ?" 

Jer.  xxxi,  29,  30:  In  those  days  they  shall  say  no  more,  The  fathers  have 
eaten  a  sour  grape,  and  the  children's  teeth  are  set  on  edge.  But  every  one 
shall  die  for  his  own  iniquity:  every  man  that  eateth  the  sour  grape,  his 
teeth  shall  be  set  on  edge. 


THE    PULP    IN    CLINICAL    DENTAL    SURGERY  225 

Ousaisthenic  Ideas. — Shakespeare  declared: 

I  had  rather  hear  a  brazen  canstick  turned, 
Or  a  dry  wheel  grate  on  the  axle-tree; 
And  that  would  set  my  teeth  nothing  on  edge, 
Nothing  so  much  as  mincing  poetry. 

— 1  Henry  IV,  iii,  i. 

Through  the  action  of  the  auditory  nerves  the  grating  of  a  dry 
wheel  or  stick  of  schoolboy's  pencil  on  his  slate  may  induce  it;  and 
not  infrequently  the  tactile  sense.  When  the  fingers  are  rubbed 
lightly  on  the  surface  of  a  piece  of  velvet,  this  curious  sensation  of 
pain  in  the  teeth  is  noticed.  Somaisthenic  ideas  become  converted 
into  a  modified  form  of  acute  odontalgia.  If  the  fingers  are  rubbed 
on  a  piece  of  glass-paper  or  a  hot  metallic  surface,  the  mind  appre- 
ciates the  condition  thus  induced  locally,  and  pain  is  felt,  not  in  the 
teeth,  but  in  the  digital  extremities  themselves. 

The  explanation  of  the  conversion  of  the  somaisthenic  percep- 
tions into  pain  would  seem  to  be  the  following: 

The  simple  act  of  touching  the  velvet  does  not  per  se  induce  pain, 
and  would  not  do  so  if  the  mental  attitude  of  the  individual  were  not 
an  anticipatory  one.  He  has  the  knowledge  that  his  teeth  will 
ache,  and  that  possibly  a  cold  tremor  will  pass  down  his  spine,  as 
his  fingers  are  brought  into  contact  with  the  velvety  field.  It  may 
be  that  the  brain  is  unaccustomed  to  determine  the  amount  of  mus- 
cular effort  set  up  by  the  digital  movements,  or  that  it  is  disturbed 
by  the  unusual  and  somewhat  naturally  repellant  act.  There  is 
no  doubt  that  there  is  a  great  limitation  to  the  capacity  of  the  syn- 
thetic action  of  our  minds  in  appreciating  the  changes  which  occur 
within  our  bodies,  and  the  mechanism  of  the  brain  frequently  fails 
in  its  estimation  and  correct  interpretation  of  what  is  going  on. 

Other  kinds  of  obscure  reflexes,  not  due  to  pathological  causes, 
may  be  cited.  Pressure  on  the  supraorbital  branch  of  the  frontal 
division  of  the  ophthalmic  nerve  may  induce  pain  in  a  maxillary 
canine.  An  observer  tells  the  author  that  when,  in  India,  he  has 
witnessed  children  sucking  sticks  of  sugar-cane,  he  himself  has  had 
toothache. 

So  it  is  obvious  that  the  optic,  the  auditory,  and  more  than 
all,  the  trigeminal  nerves,  are  closely  associated  with  these  reflex  acts 
in^^health  as  well  as  in  disease,  and  that  as  diseases  of  the  teeth, 
caries  and  the  like,  will  produce  reflex  disturbances  in  the  organs  and 
parts  supplied  by  them,  so  they,  conversely,  under  certain  forms  of 
irritability  will  set  up  odontalgia. 


2  26  THE    DENTAL    TISSUES 

RECEPTIVITY    OF    THE   PULP:    ITS  HYPERESTHESIA  AND 
DYSESTHESIA 

But  ordinarily  no  pain  is  felt;  when  it  is,  however,  the  condition  of 
the  pulp  is  that  of  dysaesthesia,  and  comes  on  only  when  the  central 
and  peripheral  nervous  systems  are  in  a  state  of  excitability  or 
receptivity. 

The  physician  is  often  brought  face  to  face  with  other  varieties  of 
hypersesthesia,  such  as  gastralgia,  enteralgia,  the  epileptic  aura,  and 
so  on.  And  the  term  dysaesthesia  is  used  in  connection  with  the  organs 
of  special  sense,  and  the  condition  indicated  by  the  appearance  of 
subjective  phenomena  referable  to  these  organs — "of  the  eye, 
by  the  appearance  of  sparks  and  flames;  of  the  ear,  by  the  perception 
of  sounds,  such  as  humming  or  buzzing;  of  the  nose,  by  the  percep- 
tion of  odors;  of  the  tongue,  by  the  perception  of  flavors"  (Bris- 
towe),  and  finally,  of  the  teeth,  by  the  recognition  of  those  interest- 
ing reflexes  to  which  allusion  has  been  made. 

(c)    DISTURBANCES    OF    THE  VASCULAR    SYSTEM   IN    THE   PULP 

Allied  to  these  morbid  states,  but  totally  different  in  origin, 
are  those  other  conditions  a  few  particulars  of  which  may  be  now 
mentioned. 

Odontalgia  of  a  severe  type  may  be  induced  by  morbid  conditions 
of  the  blood,  which  circulating  through  the  vessels  of  the  pulp 
produces  pain  and  organic  change  in  that  tissue. 

Increased  intradental  blood  pressure.  To  Dr.  Ferdinand  Tanzer 
{Oesterr-ung.  Vierteljahrsschrift  f.  Zahnheilkunde,  1907)  belongs  the 
credit  of  first  drawing  attention  to  the  effects  of  increased  blood- 
pressure  in  the  pulp.  If  a  pulp  is  very  small,  as  the  result  of  ana- 
tomical overgrowth  or  developmental  defects  of  the  hard  parts, 
or  is  habitually  anaemic  as  a  result  of  systemic  disturbances,  any 
rise  of  blood  pressure  in  it  may  induce  pain.  It  is  first  dysaesthetic, 
then  hyperaesthetic,  and  then  hyperaemic,  and  lesions  of  the  vascular 
system  may  follow,  leading  ultimately,  if  long  continued,  to  fibroid 
degeneration,  death,  and  gangrene. 

The  causes  of  these  obscure  forms  of  odontalgia  may  be  divided 
into  (i)  congenital  and  (ii)  acquired. 

The  former  are  associated  with  puberty  and  the  catamenia. 
The  signs  and  symptoms  are  as  follow:  Severe  pain  in  apparently 
normal  teeth,  generally  occurring  in  girls  and  women,  which  are 


THE    PULP    IN    CLINICAL    DENTAL    SURGERY 


227 


agonizing  in  character  and  practically  resistant  to  dental  thera- 
peutics.    There  is  no  obvious  lesion. 

If  a  tooth  is  removed  and  examined  microscopically  it  may  happen 
that  a  marked  congenital  defect  can  be  noticed.  If  the  pulp  is  too 
small  for  the  tooth — if  the  area  of  the  pulp  is  diminutive  and  that 
of  the  hard  parts  unduly  large,  indicating  that  enamel  and  dentine 
have  been  produced  at  the  expense  of  the  soft  tissues  (as  in  Fig. 


Fig.  205. — Longitudinal  section  of  molar  showing  small  size  of  pulp  and  great 
thickness  of  hard  parts.  (History  of  tooth  narrated  in  text.)  d.  Dentine;  p. 
Pulp;  c.   Cementum.      Magnified  12  times. 


205) — the  increased  blood  supply  would  probably  be  attended  by 
pain,  partly  because  the  small  size  of  the  pulp  reduces  its  trophic  in- 
fluences on  the  tooth  itself ,  partly  because  of  the  hydrostatic  conges- 
tion that  has  taken  place,  partly  because  of  the  absence  of  a  collat- 
eral circulation,  and  partly  because  the  character  of  the  chemical 
constituents  of  the  blood  is  altered  at  these  periods. 

Thus,  it  has  been  proposed  by  Dr.  Blair  Bell,  Proceedings  Royal 


2  28  THE   DENTAL   TISSUES 

Society  of  Medicine,  1908 — who  claims  that  the  metabohc  processes 
concerning  the  calcium  economy  exercise  an  all-important  influence 
upon  the  genital  functions  and  are  necessary  factors  therein — that 
the  well-known  vaso-dilatation  which  occurs  in  the  combs  and  wat- 
tles of  laying  hens  is  due  to  the  drop  in  {i.e.  loss  of)  the  calcium 
contents  of  the  blood,  whereby  a  sort  of  chilblain  condition  is 
produced. 

If  vaso-dilatation  or  local  hypergemia  can  occur,  as  suggested,  in 
the  peripheral  organs  of  the  hen,  it  is  conceivable  that  a  rise  of 
blood  pressure  in  the  pulp  can  also  be  produced  in  similar  circum- 
stances. Such  a  case,  to  which  allusion  has  been  made,  occurred 
in  the  practice  of  a  friend  of  the  author,  to  whom  he  is  indebted  for 
the  following  particulars : 

Notes  on  a  Case  of  Obscure  Odontalgia 

"October  14,  1906.  Miss  A.,  aged  fourteen.  No  caries.  Pain 
experienced  along  the  upper  and  lower  jaws  on  the  left  side.  All 
teeth  were  painful  on  pressure  and  slightly  loose.  Pain  in  joints. 
Saliva,  very  acid.     Pain  more  intense  during  cold  or  damp  weather. 

''Diagnosis:  Rheumatism  of  jaws. 

"The  patient  was  sent  to  a  physician  who  reported:  'Patient  suf- 
fering on  October  24,  1906,  from  slight  rheumatism  and  hyperchlor- 
hydria.     The    latter  was    rapidly  cured  by  the  administration  of 

magnesium  peroxide Later  on  (June  1907),  when  I  saw 

the  sections  of  the  patient's  teeth,  I  thought  that  the  trouble  might 
be  due  to  deficiency  of  calcium  salts  and  a  lower  coagulability  of  the 
blood.  I  therefore  put  her  on  a  course  of  calcium  lactate.  I  saw 
her  three  weeks  later,  when  I  ordered  her  to  continue  the  treatment 
for  a  full  six  weeks  in  all,  and  have  not  seen  her  since.' 

"The  dental  pain  gradually  departed. 

"May  I,  1907:  For  four  days  patient  complained  of  intense  pain 
in  the  left  mandibular  second  molar.  Tooth  tender  on  percussion; 
affected  by  temperature.  Local  and  internal  remedies  of  no  avail 
for  any  length  of  time. 

"Diagnosis:  Presence  in  pulp  of  pulp  nodules. 

"May  7th:  Extracted  tooth:  Too  tender  to  bur  out.  Tooth  sub- 
mitted to  microscopical  examination;  no  pulp  nodules  on  section- 
ising  (see  Fig.  205). 

"June  7th:  Great  pain  in  left  mandibular  first  molar;  symptoms  as 
before.     It  was  thought  the  condition  might  be  due  to  extra  blood 


THE    PULP    IN    CLINICAL   DENTAL    SURGERY  229 

pressure  in  the  pulp.  Tried  all  local  and  internal  remedies  as  before. 
The  only  thing  that  reheves  the  pain  is  abstraction  of  blood  by 
leeches,  but  the  effect  is  only  for  a  few  hours. 

"June  20th:  Extracted  tooth.  Sent  the  patient  again  to  the  phy- 
sician to  have  blood  tested. 

"Between  last  date  and  March  1908  patient  complained  of  pain,  at 
times  in  the  left  maxillary  second  molar,  but  the  physician's  treat- 
ment after  three  doses  generally  relieved  the  pain. 


■M  \    ^    > 


') 


s 


"v 


^•U    ^v 


Fig.   206. — Longitudinal    section  of    premolar    of   child,      p.   Pulp;    d.    Dentine; 
P.N.   Pulp  nodule.      Magnified  12  times. 

"March  12,  1908:  Great  pain  experienced  in  left  maxillary  second 
molar;  insomnia.  Applied  leeches,  with  some  reUef.  Found  a 
small  pinhole  cavity,  but  drilling  gave  rise  to  intense  pain.  Pa- 
tient had  an  anaesthetic  and  then  the  pulp  was  drilled  into.  Great 
relief  followed,  accompanied  by  much  haemorrhage.  This  having 
ceased,  I  removed  the  pulp  under  cocaine  pressure  anaesthesia.  The 
root-canals  were  very  small.  Filled  them  with  hght  dressing, 
with  temporary  gutta-percha  in  cavity. 


230  THE   DENTAL   TISSUES 

"March  19th:  Filled  root-canals  and  filled  the  tooth. 

"June  nth:  Great  pain  all  night  in  the  tooth.  Applied  aconite 
and  iodine,  with  no  result.  Drilled  into  canals  left  open,  then  ap- 
plied a  light  dressing. 

"June  12th:  Pain  getting  worse;  patient  up  all  night;  tooth  very 
tender.  Extracted  tooth.  Canals  were  all  open;  two  roots  cov- 
ered slightly  with  glairy  exudation,  one  of  them  having  a  slight 
nodule  and  slight  absorption. 


Fig.  207. — Longitudinal  section  showing  fibroid  degeneration  of  pulp  in 
deciduousi incisor,  d.  Dentine;  p.  Pulp;  a.  Abraded  area  of  dentine.  Magnified 
12  times. 

"The  gums  were  always  normal — never  injected  or  tender,  except 
in  the  last  instance,  when  they  were  sKghtly  tender." 


PHASES    or    DEGENERATION 

Acquired  lesions  are  those  of  the  vessel  walls  induced  by  such  sys- 
temic disturbances  as  are  found  in  anaemia,  chlorosis,  gout,  maras- 


THE    PULP    IN    CLINICAL    DENTAL    SURGERY  23 1 

mus,  etc.  Here  more  or  less  permanent  injury  is  done  to  the  coats 
of  the  arteries  and  veins,  resulting  in  haemorrhage,  thrombosis, 
chronic  endarteritis,  calcareous  degeneration,  and  so  on. 

If  calcareous  degeneration  in  the  form  of  pulp  nodules  (see  Fig. 
206)  or  attached  new  growth  occurs,  and  is  profound,  the  symptoms 
are  similar  to  those  of  developmental  origin,  but  the  result  of  the 
treatment  is  not  the  same,  inasmuch  as  extraction  of  the  apparently 
sound  tooth  immediately  cures  the  odontalgia. 

If  the  former  conditions  exist  there  is  little  if  any  pain  complained 
of.  The  patients  are  young  children,  but  the  pulps  are  approaching 
senility,  as  is  evidenced  by  their  exhibiting  various  phases  of  re- 
ticular atrophy  or  fibroid  degeneration  (see  Fig.  207). 

This  degeneration  is  extremely  comriion,  and  is  probably  due,  as 
a  complication,  to  thrombosis  of  the  capillaries  and  veins,  and  as  a 
result  the  impairment  of  the  vaso-motor  mechanism,  which  leads 
to  vaso-dilatation  and  diseases  of  the  vessel  walls  generally. 

OBSCURE    CAUSES    OF    ODONTALGIA 

Odontalgia  may  thus  occur  in  teeth  unaffected  by  dental  caries. 
It  is  then  due  to  one  of  the  following  causes: — A.  Increased  or 
diminished  blood  pressure  in  the  pulp;  B.  Pulp  nodules;  C.  Altered 
chemical  constituents  of  the  blood;  D.  Intra-oral  electrical  im- 
pulses; E.  Reflex  from  the  tongue;  F.  Lesions  of  Vth  nerve;  G. 
General  neurasthenia  and  debility. 

In  conclusion,  these  remarks  on  non-carious  and  non-apparent 
lesions  of  the  pulp  may  be  epitomized  by  saying  that,  as  this  organ 
is  influenced  pathologically  by  general  diseases  of  the  nervous  and 
vascular  systems,  obscure  cases  of  odontalgia  should  always  be 
regarded  from  the  standpoint  of  the  physician  as  well  as  of  the  dental 
surgeon;  and  that,  if  there  is  a  marked  personal  or  family  history  of 
gout,  rheumatism,  or  allied  conditions,  pulp  nodules  may  be  diag- 
nosed; if  the  patient  is  ansemic,  chlorotic,  or  marantic,  or  recovering 
from  a  long  febrile  disease,  early  stages  of  fibrosis  may  be  suspected; 
also  that  hypersesthesia  or  dyssesthesia  is  indicated  when  a  patient 
is  neurotic,  or  neurasthenic,  or  subject  to  "nerve  storms,"  or  is 
suff'ering  from  a  form  of  nervous  excitability  or  exaltation,  or  per- 
haps exhaustion. 


CHAPTER  IX 

THE  VASCULAR  LESIONS  OF  THE  DENTAL  PULP 

Introductory — Anatomical     considerations — General     effects — Histo-pa- 
thology — Causes — Clinical  significance. 

INTRODUCTORY 

Of  all  the  different  tissues  that  go  to  form  the  component  parts 
of  a  tooth,  the  pulp  is  the  most  interesting.  It  is  likewise  the  most 
important,  for  on  its  vascular  and  nervous  mechanism  depends  the 
vitality  and  therefore  the  utility  of  each  unit  of  the  masticatory 
apparatus.  The  strikingly  singular  character  of  the  anatomical 
distribution  of  the  vascular  supply  arrests  attention,  and  the 
impartial  observer,  who  might  be  suddenly  called  upon  to  study 
fully  and  critically  the  diseases  of  the  pulp  as  an  entirely  new  field 
for  his  own  exploitation,  would  probably  note  that  fact  at  the  com- 
mencement of  his  laboratory  experiments  and  experience. 

ANATOMICAL    CONSIDERATIONS 

Two  facts  stand  out  pre-eminently  as  being  of  great  significance — ■ 
(i)  the  absence  of  a  collateral  circulation  in  the  pulp  itself,  and  (2) 
the  non-valvular  character  of  the  veins,  which  at  the  same  time  are 
non-collapsible. 

(i)  With  regard  to  the  former,  it  may  be  recalled  that  during  the 
development  of  the  teeth  the  tissues  formed  from  each  layer  of  the 
primitive  blastoderm  are  supplied  by  two  separate  groups  of  vessels, 
of  which  the  internal  set,  distributed  to  the  mesodermic  structures, 
vascularize  the  dentine  papilla,  the  dental  sac,  and  the  surrounding 
bone.  In  adolescent  and  adult  pulps  the  branches  of  the  internal 
set  enter  the  apical  foramina  of  the  teeth  usually  as  a  single  trunk, 
which  may  measure  as  much  as  83^1  in  width,  to  become  almost 
immediately  bifurcated  and  divided  into  many  subsidiary  branches, 
ending  near  the  basal  layer  of  Weil  in  an  anastomosis  of  capillary 
loops  whose  individual  lumina  are  roughly,  on  the  average,  about 
8m  in  diameter  (see  Chap.  VII,  Vol.  I). 

232 


THE   VASCULAR    LESIONS    OF    THE    DENTAL   PULP  233 

If  the  lumen  of  the  main  artery,  entering  the  apical  foramen, 
is  by  any  means  occluded,  the  integrity  of  the  whole  of  the  vascular 
system  is  imperilled,  as  there  are  no  collateral  branches  to  restore 
the  balance  in  the  blood-stream.  This  actual  condition  is  almost 
if  not  quite  unique  in  the  general  anatomy  of  the  body. 

These  remarks  apply  with  no  element  of  uncertainty  to  the 
vascular  system  of  the  single-rooted  teeth.  It  cannot,  however, 
be  asserted  with  equal  confidence  that  the  pulps  of  molars  have  no 
collateral  circulation.  The  exact  method  of  distribution  in  these 
larger  teeth  has  never  been  ascertained,  owing  to  the  difficulties 
encompassing  the  performance  of  an  artificial  injection  of  the  vessels 
in  adult  age.  But  clinically  it  would  seem  to  be  impossible  for  a 
collateral  anastomosis  to  exist;  and  from  an  embryological  point  of 
view  the  statement  of  Lepkowski  may  most  probably  be  relied 
upon.  This  observer  shows  {Anatomischer  Hefte,  1901)  that  "In 
the  germ  of  the  two-cusped  tooth  there  are  present  two  bundles 
of  vessels  separated  from  one  another,"  etc.  (seeChap.XII,  Vol.  I). 

(2)  Again,  on  account  of  the  patency  and  non-valvular  character 
of  the  veins  it  may  be  assumed  that  exogenetic  influences  in  normal 
circumstances  cannot  affect  the  flow  of  blood  in  the  pulp.  The  veins 
are  not  subjected  to  muscular  or  other  external  pressure,  and  in 
this  respect  agree  with  other  similarly  constructed  tubes,  such  as  the 
superior  and  inferior  vena  cava,  the  pulmonary  veins,  and  those  in 
the  interior  of  the  cranium  and  vertebral  column,  and  long  and 
short  bones. 

Hence  it  is  observed  that  these  two  facts  are  conspicuously 
apparent,  the  first  being  probably  of  the  greater  importance,  as  the 
general  systemic  veins  that  are  2  mm.  and  less  in  diameter  are  un- 
provided with  valves.  But  the  significance  of  the  absence  of  a 
collateral  circulation  on  the  causation  of  diseases  of  the  pulp  cannot 
be  overestimated  by  the  perspicacious  and  discriminating  student. 

GENERAL   EFFECTS 

After  due  consideration  of  these  anatomical  conditions  it  is  not  a 
matter  for  surprise  that  lesions  or  degenerations  arising  from  varia- 
tions in  the  blood  current  or  in  the  blood  pressure  in  the  dental  pulp 
should  be  fairly  common.  So  much  is  this  the  case  that  one  would 
probably  be  not  far  from  the  truth  in  asserting  that,  while  teeth  are 
so  very  frequently  the  victims  of  dental  caries,  they  may  also 
equally  and  simultaneously  be  subjected  to  internal  retrogressive 


234 


THE    DENTAL    TISSUES 


.\\^^'\""% 


Wv"^m 


^  \ 


7/ 


Fig.  2o8. — Longitudinal  coronal  section  of  premolar  with  pulp  in  situ,  showing 
thrombosis  of  capillaries  and  other  vascular  lesions.  Prepared  by  the  Author's 
process;  stained  with  Ehrlich's  acid  hagmatoxylene.  a.  Branch  of  main  artery; 
V.  Enlarged  vein;  c.  Capillary  filled  with  thrombus;  x.  Thrombus  becoming 
organised;  f.  Early  stage  of  fibrification  of  pulp  tissue  proper;  o.  Odontoblast 
layer  increased  in  width  and  in  the  number  of  its  cells.      Magnified  45  times. 


THE   VASCULAR    LESIONS    OF    THE    DENTAL    PULP  235 

changes  induced  by  a  lowered  or  altered  physiological  resistance 
on  the  part  of  the  pulp,  through  the  unusual  characteristics  of  its 
blood  supply.  This  does  not  apply  entirely  to  the  normal  individual, 
but  more  especially  to  those  persons  who  suffer  from  disturbances  of 
the  circulatory  system. 

It  is  well  known  that  many  persons  undergo  a  certain  temporary 
discomfort  brought  about  by  hyperaemia  of  the  pulp.  For  some 
reason  or  other  the  vessels  become  vicariously  over-filled  and  undergo 
hydrostatic  congestion,  which  presently  disappears  when  the  cause 
is  removed  or  when  there  is  a  good  outlet  provided  for  a  free  flow. 
If,  however,  the  intradental  pressure  is  so  severe  as  to  prevent  the 
occurrence  of  an  efficient  and  quick  relief,  then  the  tissues  degenerate 
and  perhaps  die,  as  they  are  unable,  on  account  of  their  dentinal 
environment,  to  accommodate  themselves  to  their  engorged  state. 

Tanzer  (see  Chapter  VIII)  records  a  case — among  others — where, 
on  account  of  the  circulatory  irregularities  in  the  internal  genital 
organs  and  adnexa  of  a  patient,  the  pulp  of  a  tooth  died  as  the  result 
of  the  abnormally  increased  intradental  blood  pressure.  The 
introduction  of  metal  fillings  and  cement  floorings  into  carious 
cavities  is  sometimes  followed  ultimately  by  local  pain,  and  the 
work  of  obturation  is  credited  by  the  uninformed  with  being  the 
cause  of  the  odontalgia,  while  it  is  merely  often  due  to  either 
reflex  nervous  irritation  or  a  rise  in  the  local  blood  pressure.  The 
writer  just  quoted  proceeds  to  summarise  his  remarks  by  saying 
that  this  increased  intradental  blood  pressure  may  arise  as  a  con- 
sequence of  diseases  due  to  circulatory  deflections  from  the  normal,  to 
conditions  of  high  nervous  tension  as  in  hysteria,  to  influenza, 
pregnancy,  or  occasionally  as  the  result  of  traumatism. 

It  is  thus  clear  that  temporary  engorgement  of  the  vessels  in 
the  pulp  tends  to  produce  odontalgia  of  varying  degrees  of  severity; 
but  if  this  congestion  be  continued  it  leads  eventually  to  death  of 
the  parts  and  cessation  of  pain.  This  may  be  brought  about  (a) 
slowly,  when  the  tissues  pass  through  the  various  stages  of  fibroid 
degeneration,  or  (6)  rapidly,  when  moist  gangrene  supervenes  as  a 
result  of  thrombosis,  and  arterio-sclerosis  and  sudden  death  en 
masse  takes  place. 

It  is  believed  that  slight  rise  of  blood  pressure  produces  no 
symptoms  of  neuralgia,  though  it  can  be  readily  conceded  that 
nerve  pain  from  other  areas  may  be  reflected  to  a  tooth  which  is 
sound  but  whose  pulp  is  somewhat  hyperaemic. 

At  the  time  that  Dr.  Henry  Head  wrote  his  remarkable  observa- 


2:^6  THE    DENTAL    TISSUES 

tions  on  "Disturbances  of  Sensation,  with  Especial  Reference  to  the 
Pain  of  Visceral  Disease,"  Brain,  Pt.  Ill,  1894,  and  drew  attention 
to  certain  well-defined  areas  of  superficial  tenderness  of  the  skin,  the 
study  of  the  vascular  lesions  of  the  pulp  had  not  been  undertaken. 
His  investigations  were  solely  concerned  with  carious  teeth,  and 
showed  that  "As  long  as  the  pulp-cavity  is  not  exposed  the  pain 
remains  local.  The  patient  will  complain  of  an  aching  tooth  and 
will  point  to  the  one  affected."  Local  stimulation  produces  local 
pain  (odontalgia),  and  "is  exactly  analogous  to  that  produced  by 
injuries  to  the  conjunctiva  or  outer  layers  of  the  cornea."  When, 
however,  the  pulp  is  exposed,  the  pain  alters  in  character  and  distribu- 
tion (neuralgia).  "It  starts  in  the  affected  tooth,  and  darts  or 
shoots  into  the  face,  forehead,  neck,  or  ear"  (page  407).  It  is 
practically  certain  that,  to-day,  increased  intradental  blood  pressure 
in  sound  teeth  would  be  added  to  Dr.  Head's  previous  classification. 

Fortunately,  gangrene  as  a  permanent  termination  of  thrombosis 
is  a  contingency  of  comparatively  infrequent  occurrence  from  a 
clinical  point  of  view,  and  it  is  with  certain  atrophic  changes, 
slowly  produced,  that  the  author  desires  to  deal  in  the  present 
chapter. 

In  Chapter  VII  the  author  gives  an  account  of  that  common 
lesion  of  the  pulp  which  is  to-day  spoken  of  as  fibroid  degeneration 
or  reticular  atrophy.  Its  etiology  is,  there,  not  thoroughly  eluci- 
dated. The  opinion  is,  however  (see  page  188),  expressed  that  it 
represents  "the  natural  and  usual  termination  of  the  life-history 
of  the  dental  pulp"  occurring  in  aged  teeth.  The  author  has 
enlarged  his  views  on  the  subject,  for  he  believes  that  the  senility 
of  the  pulp  does  not  at  all  depend  upon  its  age.  Children  may  at 
times  possess  senile  pulps,  in  the  same  way  that  the  eyes  of  young 
persons  often  exhibit  the  arcus  senilis  of  the  cornea.  Much  of  the 
material  examined  for  the  purpose  of  this  Chapter  was  removed 
for  the  treatment  of  irregularities  in  position  of  the  teeth,  and  many 
sections  show  that  the  whole  of  the  dentinal  wall  was  not  completely 
calcified. 

Probably  this  fibrosis  or  sclerosis  is  due,  as  a  complication,  in 
the  first  place  to  thrombosis  of  the  capillaries  and  veins,  and  per- 
manent dilatation  through  loss  of  tone  (due  to  impairment  of  the 
vaso-motor  mechanism)  or  disease  of  the  walls  of  the  arteries,  with 
or  without  tiny  haemorrhages.  This  seems  often  to  be  succeeded 
or  accompanied  by  a  condensation  or  fibrification  of  the  pulp  tissue 
which  lies  between  the  basal  layer  of  Weil  and  the  substance  of  the 


THE   VASCULAR    LESIONS    OE    THE    DENTAL    PULP  237 


238  THE    DENTAL    TISSUES 

pulp  proper.  A  hyperplasia  of  the  connective  tissue  fibres  of  the 
parts  occur.  "Sheaving"  of  the  odontoblasts,  with  or  without 
fatty  degeneration,  permanent  distension  of  the  arteries  and 
arterioles,  and  rapid  development  of  overgrowth  of  the  fibroid 
tissue  supervene,  until  a  well-marked  reticular  atrophy  appears, 
and  in  later  stages  complete  fibrosis  of  the  organ,  with  disappearance 
of  all  cells  and  nuclei,  and  every  vestige  of  nerve  bundle  and 
vascular  system. 

HISTOLOGY 

Longitudinal  coronal  sections  of  the  pulps  show  to  the  best 
advantage  these  changes.  The  capillaries  and  small  veins  which  are 
distributed  to  the  peripheral  parts  are  engorged.  Very  few  are 
empty  and  none  are  stenosed.  Under  low  powers  of  the  microscope 
they  present  themselves  as  dark  long  strands  running  for  the  most 
part  in  the  vertical  axis  of  the  tooth.  The  corpuscles  and  blood 
platelets  which  they  contain  are  appreciably  altered  in  shape  and 
size — -due,  no  doubt,  partly  to  post-mortem  changes,  partly  to  the 
histological  reagents  employed — as  these  have  not  been  specially 
directed  to  the  preservation  and  staining  of  the  blood  elements — 
and  partly  also  to  those  haemic  changes  which  favour  coagulation, 
to  be  presently  described.  They  may  partially  or  completely  fill 
the  lumina  of  the  vessels,  and  are  sometimes  arranged  in  rouleaux; 
but  in  addition  have  in  places  escaped  from  their  walls  as  a  con- 
sequence of  rupture.  Small  arterial  cauliflower-like  haemorrhages 
are  seen  frequently,  at  times  among  the  odontoblasts,  at  times  iri 
the  basal  layer  of  Weil,  and  again  at  times  in  the  substance  of  the 
pulp  itself.  The  haemorrhagic  infarcts  may  vary  in  constitution 
from  a  punctiform  collection  of  a  dozen  or  more  corpuscles,  to  a 
large  mass,  as  in  the  photomicrographs.  The  endothelium  of  the 
tunica  intima  of  these  arteries  and  capillaries  is  altered,  and  the 
nuclei  of  its  cells  are  indistinguishable.  The  larger  arteries  and 
larger  veins  are  empty,  as  exemplified,  and  hyaline  areas  of  degen- 
erated material  in  many  places  extend  across  them,  and  as  they 
become  smaller  occlude  their  lumina.  The  arteries  have  lost  their 
distinguishing  coats,  and  so  have  the  veins,  both  classes  of  vessels 
having  thinner  walls  than  usual — a  condition  which  pathologists 
would  probably  designate  as  hypoplasia  or  hyaline  degeneration 
(Fig.  220). 

The  morphological  effects  of  these  vascular  lesions  on  the  sur- 
rounding  soft  parts   is   very  noticeable.     In   some   instances   the 


THE  VASCULAR   LESIONS    OF   THE   DENTAL   PULP 


239 


N     ft 


W     OS 


Q    03    aj 


e  o 


y::  "o 


fc!    c    9^   ^ 


tS3  ,Q  q:1  I 


240 


THE    DENTAL    TISSUES 


odontoblasts,  which  are  largely  increased  in  numbers,  are  vacuolated 
and  fatty  (Fig.  221,  o),  the  globules  being  often  situated  at  their 
basal  extremities,  very  numerous,  and  very  small  as  a  rule,  but  occa- 
sionally as  wide  as  the  cells  themselves.  They  (the  cells)  are  flattened 
laterally,  and  their  nuclei  are  planiform.  They  are  gathered  together 
into  bundles  or  sheaves  (Fig.  212).  The  "sheaving"  of  the  odonto- 
blasts is  of  very  common  occurrence.  It  has  been  noticed  by  other 
writers,  particularly  by  Walkhoff,  who  gives  photomicrographs  of 


7  j^*tJf  if*»5Wff5-y 


■— D 


Fig.  211. — Details  of  early  fibrification  of  pulp  tissue,  d.  Dentine;  o. 
Odontoblasts;  c.  Condensation  of  pulp  tissue;  p.  Early  fibrosis.  Magnified  250 
diameters. 


it  in  his  "Atlas  of  the  Pathological  Histology  of  the  Human  Teeth," 
1903.  The  basal  layer  of  Weil  is  curiously  rich  in  small  cells  which 
have  large  round  nuclei,  and  perhaps  somewhat  diminished  in 
width,  while  its  fibrous  components  are  rendered  more  prominent 
and  tough. 

The  cells  of  the  pulp  proper  possess  nuclei  which  are  degenerate 
in  shape  and  small  in  size;  their  branches  are  increased  in  number 
and  extremely  well  marked.  Here  and  there,  in  varying  degrees 
of  intensity,  there  seems  to  be  a  thickening  of  the  intercellular 
cementing   substances  and   chemical   changes  in  the  cytoplasm  of 


THE   VASCULAR    LESIONS    OF    THE    DENTAL    PULP 


241 


the  cells.  When  nerve  bundles  are  visible,  they  appear  to  be  degen- 
erated also,  and  for  the  time  being  usually  stain  badly  as  long, 
thin,  dark  threads  running  alongside  the  vessels. 

Organization  of  the  thrombi  is  observed  to  be  proceeding  in  places, 
leaving  only  a  thin  fibrous  cord  or  hyaline  plug  coherent  to  the 
walls  or  completely  filling  it  up. 


Fig.   212. — Degeneration  of  odontoblasts.      Magnified  500  diameters. 


ETIOLOGY 

Turning  from  the  patho-histological  aspect  of  this  study,  it  is 
expedient  and  useful  to  inquire  what  possible  factors  have  contrib- 
uted to  bring  about  this  condition.  Why  has  the  blood  coagu- 
lated? Why  have  the  vessels  become  thrombosed  and  the  soft 
tissues  degenerated?  Probably  the  absence  of  a  collateral  circu- 
16 


242 


THE    DENTAL    TISSUES 


A-- 


F  .-. 


'  '.  /  ' 

;' w-i 


S^' 


Fig.  213. — Similar  to  Fig.  208,  showing  a  later  stage  of  fibrosis  of  the  pulp. 
D.  Dentine;  o.  Odontoblasts  increased  in  number;  a.  Arteriole;  h.  Hsemorrhagic 
infarct;  f.   Fibrosis  of  pulp.      Magnified  45  times. 


THE   VASCULAR    LESIONS    OF    THE    DENTAL    PULP 


243 


lation  predisposes  to  it;  but  its  exciting  causes  cannot  be  so  readily- 
determined.  This  absence  of  collateral  circulation  would  predispose 
to  the  onset  of  thrombosis  in  cases,  also,  where  any  obstruction 
of  outflow  existed,  e.g.,  in  cases  of  inflammation  around  the  soft 
parts,  or  inflammation  in  the  soft  tissues  themselves.  The  vessels 
quickly   become   thrombosed,   for   instance,   after   the   application 


Fig.    214. — Details  of  blood-vessels,      c.  Corpuscles  adherent  to  vessel  walls; 
X.    Nerve  bundles;   p.    Degenerated  pulp  tissue.      Magnified  500  diameters. 

of  arsenious  acid  to  an  exposed  surface  of  the  pulp,  because  the 
vessels  are  under  hydrostatic  conditions  and  inclosed  in  a  resisting 
wall  of  dentine.  Any  increased  volume  of  fluid  (blood)  must  be 
compensated  by  a  corresponding  outpouring — as  there  cannot  be 
an  adequate  displacement  of  the  surrounding  parts,  owing  to  their 
circumscriljcd  nature — to  afford  the  room  required.     (It  must  not 


244 


THE    DENTAL    TISSUES 


Fig.  215. — Pulp  in  situ.  h.  Hasmorrhage  near  basal  layer  of  Weil;  o.  Odonto- 
blasts; D.  Dentine;  a.  Hyaline  mass  in  small  artery;  F.  Fibroid  pulp.  Magni- 
fied 250  diameters. 


H  .-■ 


Fig.  216. — Similar  to  preceding  (same  magnification),  h.  Hcemorrhagic 
infarct;  R.  Ruptured  artery  whence  blood  corpuscles  have  escaped;  D.  Dentine; 
o.  Odontoblasts. 


THE   VASCULAR    LESIONS    OF    THE    DENTAL    PULP  245 


Fig.   217. 


-Similar    to    preceding    (same    magnification),   showing  hemorrhagic 
infarct. 


i  -  ':^^T 


Fig.   2i«. — 


Similar    to    preceding    (same    magnification),   showing  htemorrhag 
infarct  in  centre  of  pulp  tissue. 


246 


THE    DENTAL    TISSUES 


be  forgotten,  also,  that  no  lymphatics  have  ever  been  identified  as 
such  in  the  pulp.)  The  thrombosis  in  this  instance,  which  might 
almost  be  regarded  as  chemical  or  traumatic,  is  an  early  stage  of 
acute  inflammation,  and  is  almost  immediately  followed  by  gangrene 
or  death  of  the  pulp  en  masse. 


Fig.   219. — Hyaline  degeneration  of  blood-vessels.      Magnified  300  times. 


A  thrombus  may  be  the  cause  or  the  result  of  arteritis  or  phlebitis. 
It  may  be  due  to  chemical  changes  in  the  blood  itself  or  lesions  in 
the  walls  of  the  vessels,  as  in  degenerations.  Osier  ^  has  observed 
that  in  thrombus  formation  the  blood  platelets,  fully  investigated  by 
Bizzozero,   Virchow's   Archives,   vol.    xc  in  1882,  and  Eberth  and 

*  Sir  William  Osier:  Cartwrigiit  Lectures  on  the  "Pliysiology  of  the  Blood 
Corpuscles,"  1886. 


THE   VASCULAR    LESIONS    OF    THE    DENTAL    PULP 


247 


Schimmelbusch,  Virchow^s  Archives,  vol.  ciii  in  1888,  are  the  first 
of  all  the  blood  elements  to  accumulate  on  the  vessel  walls  during 
coagulation,  and  that  the  filaments  of  fibrin  spread  principally 
from  these  plate  masses.  They  undergo  viscous  metamorphosis 
and  also  conglutination  as  explained  by  Thoma.^ 


">, 


X 


Fig.   220. — Thrombosis  and  hyaline    degeneration    of  arteries. 

times. 


Magnified    500 


The  thrombi  formed  in  the  sections  which  form  the  subject  of 
this  chapter  are  obviously  neither  entirely  the  "  red  "  nor  the  "  white  " 
varieties,  but  are  clearly  for  the  most  part  of  a  hyaline  character, 
consisting  of  cells,  platelets,  fibrin  filaments,  and  a  colourless,  semi- 
transparent,  homogeneous  material.     They  are  entirely  non-infected, 

^Thoma:  "Text-book  of  General  Pathology,"  1896. 


248 


THE    DENTAL    TISSUES 


although  hyahne   thrombi  are  generally  associated  with  infected 
conditions. 

Thus  it  would  seem  that,  in  the  dental  pulp,  chemical  changes 
in  the  blood,  plus  the  unusual  arrangement  of  the  terminal  vessels, 
assisted  by  the  vis  a  tergo  which  naturally  leads  to  a  certain  amount 


Fig.   221. — Details     of    Fig.    215       h.    Hasmorrhagic    infarct;    r.  Rupture  of 
blood-vessel;  d.   Dentine;  o.  Vacuolated  odontoblasts;  f.  Early  fibrosis  of  pulp. 

Magnified  250  times. 

of  retardation  of  the  flow  and  therefore  coagulation — as  first  pointed 
out  by  Virchow — are  the  originators  of  the  atrophy,  through  loss 
of  trophic  influences.  The  chemical  changes  are  those  undergone 
by  the  blood  through  systemic  derangements  such  as  anaemia, 
chlorosis,  and  those  which  take  place  toward  the  end  of  exhaustive 
diseases. 


THE   VASCULAR    LESIONS    OF    THE    DENTAL    PULP 


249 


The  suggestion  of  infectivity  can  be  at  once  dismissed,  as  all  the 
sections  which  have  come  under  the  author's  notice  have  been 
obtained  from  teeth,  of  the  young  and  old  alike,  whose  macro- 
scopical  aspects  appeared  to  be  sound. 

It  is  of  course  well  known  that  the  blood  of  chlorotic  patients  may 
especially  tend  to  produce  diseases  of  the  vessel  walls — due,  no  doubt, 


"'■  H 


Fig.    222. — Reticular    atrophy    of  pulp  with  thrombosed  capillaries,      h.   Small 
hemorrhage  near  thin-walled  vessel.      Magnified  300  times. 

to'the  great  diminution  of  red  corpuscles  and  the  relatively  greater 
number  of  leucocytes,  and  their  slow  movement  along  the  walls 
of  the  vessels,  together  with  an  increased  number  of  platelets. 
Marantic,  anaemic,  and  debilitated  conditions  which  often  form  the 
sequela;    of    long-continued    and    enfeebhng    fevers    and    diseases, 


250 


THE    DENTAL    TISSUES 


probably  also  have  the  same  or  similar  effects  on  the  tissues  of  the 
vascular  system. 

The  cases  here  presented  are  entirely  free  from  intrinsic  calcifica- 
tion, are  unaccompanied  by  the  formation  of  adventitious  dentine  or 
any  amyloid  or  fatty  degeneration  of  the  pulp;  and  in  no  specimen 


Fig.    223. — Nearly  normal  pulp  passing  into  a  reticular  condition.      Magnified. 

300  times. 

yet  examined  by  the  author  have  there  been  evidences  of  chronic 
arteritis,  atheroma  or  endarteritis,  aneurysmal  varix,  phlebitis, 
or  varicosity  of  the  veins. 


CLINICAL    SIGNIFICANCE 


Of  what  value  to  the  dental  surgeon  is  a  knowledge  of  the  patho- 
logical states  sketched  in  the  preceding  pages?     Can  it  assist  him 


THE   VASCULAR    LESIONS    OF    THE    DENTAL    PULP 


!5I 


in  the  more  perfect  performance  of  his  daily  duties?  Certainly; 
for  it  is  at  once  obvious  that  if  an  attempt  be  made  to  "cap"  an 
exposure  of  a  pulp  which  happened  to  be  diseased  in  this  way,  no 
matter  how  carefully  or  how  aseptically  the  operation  be  done, 
no  new  secondary  or  adventitious  dentine  would  be  produced  to 


Fig.    224. — Details    of    thrombosis,      c.   Thrombosed    capillary;    a.  Artery;    n. 
Myelinic  nerve  bundle.      Magnified  250  times. 


heal  the  hireach  of  surface;  and  also  the  obstacles  surrounding  the 
complete  devitalization  of  the  pulp  by  means  of  arsenious  acid,  or 
its  painless  extirpation  by  means  of  pressure  anesthesia,  become 
immediately  manifest  and  indisputable.  It  is  of  course  acknowl- 
edged that  thrombosis  and  fibrosis  are  undiagnosable  during  life, 
but  they  may  always  be  suspected  in  weak  or  marantic  patients. 


2^2 


THE    DENTAL    TISSUES 


Pig.  225. — General  view  of  pulp  in  situ,  showing  an  intermediate  phase  of 
fibroid  degeneration;  longitudinal  median  section  of  canine,  a.  Thrombosed 
artery;  d.  Dentine;  d'.  d'.  Internal  wall  of  dentine  showing  clefts  probably 
due  to  molecular  changes;  p.  Pulp  tissue  beginning  to  degenerate.  Magnified 
45  times. 


THE    VASCULAR    LESIOXS    OF    THE    DENTAL    PI'LP  253 

The  knowledge  might  perhaps  explain  the  deaths  of  pulps  where 
no  e\T.dent  lesion  could  be  ascertained. 

And,  finally,  it  is  not  difficult  to  believe  that,  when  the  blood  svs- 
tem  of  the  pulp  is  deranged  in  the  way  already  described,  it  is  de- 
prived of  its  trophic  functions  with  regard  to  the  tissues  around. 
Teeth  lose  their  accustomed  \4tality  and  become  more  susceptible 
to  outside  influences  and  disturbances.  At  first  remaining  in 
situ,  though  affected  by  fibrosis,  which  exists  unknown  both 
subjectively  and  objectively,  the  degenerated  pulp  mav  begin 
to  transmit  its  lowered  vitality  to  the  dentine  and  the  periodontal 
membrane.  The  former  most  probably  is  deprived  of  its  proto- 
plasmic nourishment,  wholly  or  in  part,  and  undergoes  more  or 
less  chemical  or  molecular  change,  and  at  times  morphological 
change  too.  as  seen  in  the  photomicrograph  (Fig.  225),  becoming 
unduly  brittle.  The  latter  may  easily  and  doubtless  does  share  in 
the  fibroid  degeneration,  which  would  assuredly  sooner  or  later  tend 
to  loosening  of  the  teeth  in  their  alveolar  sockets.  It  may,  in  addi- 
tion, be  hinted  that  perhaps  this  condition  of  lowered  vitality  may 
predispose  the  teeth  to  the  onset  of  dental  caries. 


CHAPTER  X 

THE    MORBID    AFFECTIONS    OF   THE    ALVEOLO -DENTAL 

PERIOSTEUM 

.  "'CROSCOPiCAL   Elements  in: — (i)    Inflammation;    (ii)    Abscess;    (iii) 
Dental  cyst;  (iv)  Innocent  and  Malignant  tumours. 

Inflammation 

Etiology. — The  causes  may  be  divided  into  local  and  general. 
Among  the  first  may  be  mentioned:  (i)  Extension  of  septic  diseases 
from  the  pulp;  (ii)  Cold;  (iii)  Application  of  drugs  or  other  irritants; 
(iv)  Mechanical  irritation  of  and  infection  around  masses  of  cal- 
culus; (v)  Traumatism,  such  as  a  blow,  fracture,  use  of  toothpick, 


Fig.     226. — Maxillary    canine  Fig.    227. — Maxillary    pre- 

with     chronic    inflammation     of       molar  with  chronic  inflamma- 
the  periodontal  membrane.  tion  of  the  periodontal  mem- 

brane. 

etc.,  and  (vi)  Systemic.  Amongst  the  latter:  (i)  Mercurial  sali- 
vation; (ii)  Systemic  dyscrasia,  e.g.,  gout,  rheumatism,  syphilis, 
struma,  etc.,  and  rarely  (iii)  Phosphorous  poisoning. 

Synonyms. — Periodontitis,  pericementitis,  etc.  It  may  be  local 
or  general;  acute  or  chronic. 

Secondary  Changes. — Resolution,  suppuration  with  sometimes 
necrosis  and  absorption  of  the  alveolar  bone. 

Macroscopical  Appearances. — The  tissue  is  more  or  less  thick- 
ened, rough,  and  blood-stained.  The  removal  of  the  tooth  im- 
parts to  it  a  ragged  appearance.  In  places  it  may  be  stripped  from 
off  the  cementum. 

2.54 


DISEASES    OF    THE    ALVEOLO-DENTAL    PERIOSTEUM  255 

Symptoms. — When  acute  there  is  pain  which  is  constant  and  dull 
in  character,  reheved  in  early  stages  by  pressure  on  the  affected  tooth, 
but  returning  when  the  pressure  is  removed.  The  tooth  becomes 
in  time  loosened;  usually  it  returns  to  its  normal  firm  condition. 
When  chronic,  pain  is  considerably  modified;  may  even  be  absent 
until  pressure  is  apphed  locally.  The  tooth  is  permanently  loosened, 
and  thus  a  great  diiiference  exists  between  the  acute  and  chronic 
conditions. 

DIFFERENTIAL    DIAGNOSIS    OF    ACUTE    INFLAMMATION    OF: 

The  Pulp  The  Periodontal  Membrane 

1.  Pain.  Sharp,  shooting,  intermit-  i.  Dull,  gnawing,  aching,  continuous, 
tent,  throbbing,  reflected.  localized. 

2.  TEMPER.A.TURE.  A.  Cold  may  give  2.  A.  Cold  generally  gives  relief.  B 
relief  in  early  stages.  B.  Heat  in-  Heat  does  not  alter  character  of 
tensifies  pain.  pain. 

3.  Inspection.     Tooth  normal  height.  3.  Tooth  raised  in  socket. 

4.  Palpation.     Tooth  firm.  4.  Tooth  loose  in  later  stages. 

5.  Percussion.     Negative.  5.  Induces  pain. 

6.  Pressure.     Negative.  6.  At  first  relieves  pain;  in  later  stages, 

intensifies  it. 

7.  Cavity.     Generally  present.  7.  No  cavity. 

8.  Pain.     Increased   on   assuming  re-       8.  Not  increased, 
cumbent  position. 

HISTOLOGY 

The  fibrous  tissue  is  infiltrated  with  inflammatory  cells  and  prod- 
ucts. These  new  cells  collect  in  masses  between  the  fibres,  and  are 
found  running  in  a  direction  chiefly  parallel  with  the  axis  of  the  root 
of  the  tooth.  Inflammatory  foci  may  form  and  suppurate,  pro- 
ducing small  localised  abscesses.  The  osteoblasts  are  particularly 
visible,  and  depositions  of  new  cementum  with  irregular  lacunse  and 
canahcuh  often  occur.  Calcospherite  spherules  may  also  sometimes 
be  found.  The  blood-vessels  are  dilated,  and  the  perivascular 
tissues  with  their  nerve  bundles  are  considerably  increased  in  size, 
as  well  as  in  the  number  of  their  individual  elements. 


A bscess 
HISTOLOGY 

.Suppurative  foci  of  varying  dimensions  may  occur  in  any  part  of 
the  periodontal  membrane.  When  of  large  size  they  are  called 
alveolar  abscesses.     The  inflammatory  process  has  passed  into  the 


256 


THE    DENTAL    TISSUES 


stage  of  suppuration,  and  according  to  the  rate  of  formation  and  the 
severity  of  the  symptoms  produces  an  acute  or  chronic  abscess.  In 
both  cases,  not  only  is  the  periodontal  membrane  affected,  but  the 
bony  sockets  also.  When  the  inflammation  becomes  chronic,  the 
membrane  becomes  extensively  thicker,  through  the  persistence  of 
the  changes  occasioned  by  the  acute  condition.  After  extraction 
of  a  tooth  thus  affected,  it  is  seen  that  large  masses  of  soft  tissue  are 
adherent  to  the  cementum.  This  soft  tissue  very  frequently  be- 
comes transformed  rapidly  into  granulation  tissue,  with  all  its  char- 


P  M 


Pig.  228. — Acute  inflammation  of  the  periodontal  membrane  in  situ.  Pre- 
pared by  the  Author's  process.  Stained  with  h^matoxylene.  Magnified  40 
times.  D.  Dentine;  c.  Cementum;  p.m.  Root  membrane,  the  fibrous  tissues  of 
which  are  crowded  with  inflammatory  cells  and  products. 

acteristic  appearances  and  consequences.  The  alveolar  socket 
becomes  absorbed,  and  if  the  process  continues,  the  cementum  in 
addition,  by  the  functions  of  phagocytes.  "  Granulomata "  have 
been  described  in  this  connection,  but  nothing  warrants  the  applica- 
tion of  this  appellation  to  the  condition,  when  the  correct  definition 
of  a  tumour  is  taken  into  consideration  (see  page  327). 

Microscopical  examination  shows  that  the  abscess  consists  of  an 
outer  firm  fibrous  sheath  forming  a  kind  of  wall,  the  fibres  of  which 
run  side  by  side  in  a  longitudinal  direction  all  closely  interlacing. 
Stretching  from  these,  inwards,  are  numbers  of  trabeculae,  composed 
of  fine  connective  tissue  dividing  the  interior  of  the  cavity  into 


DISEASES    OF   THE   ALVEOLO-DENTAL  PERIOSTEUM  257 


Fig.   229. — The    same  as  the  preceding.      Magnified  250  times,     f.   Connective 
tissue  ("principal")  fibres;  i.   Inflammatory  cells  and  products. 


Fig.   230. — Another  part  of  the  same.      Magnified  250  times. 


17 


258 


THE    DENTAL    TISSUES 


septa  or  compartments  of  varying  size  and  shape.  Each  is  filled 
with  round  or  squarish  cells  of  large  dimensions.  In  the  centre  of 
all,  the  majority  of  the  pus  cells  have  escaped  during  the  extrac- 
tion of  the  tooth,  the  force  of  which  has  ruptured  the  wall. 


c  T 


Fig.  231. — A  section  through  a  chronic  abscess  of  the  periodontal  raembrane. 
Stained  with  hsematoxylene.  Magnified  50  times.  c.T.  Capsule  of  fibrous 
tissue;  M.  Connective  tissue  cells;  c.  Cavity  occupied  by  liquor  pur  is  and  pus 
corpuscles. 


Dental  Cyst 
Definition. — A  cystic   degeneration    of  the  epithelial  "rests' 


of 


the  periodontal  membrane,  produced  as  a  result  of  inflammation 
of  that  tissue,  containing  some  viscid  fluid  and  holding  crystals  of 
cholesterine  and  other  salts  in  suspension,  and  lined  with  epithelium 


DISEASES    OF   THE   ALVEOLO-DENTAL  PERIOSTEUM  259 

Etiology. — Two  hypotheses  are  prevalent  as  to  its  origin — ■ 
(A)  the  mesodermic  and  (B)  the  ectodermic. 

(A)  The  former  is  based  on  the  beHef  that  either  (i)  granulation 
tissue  having  attained  a  considerable  size  may  break  down,  and 
caseate,  or  (ii)  a  chronic  abscess  may  secrete  a  fluid.  (B)  The  latter 
is  the  theory  fully  investigated  and  described  by  J.  G.  Turner/  who 
has  conclusively  proved  that  minute  quantities  of  septic  products 
from  the  pulp  cavities  of  dead  teeth,  setting  up  a  chronic  inflamma- 
tion of  the  periodontal  membrane  may  stimulate  to  activity  and 
rapid  growth  the  paradental  epithehal  "rests"  of  Malassez  ("debris 
epitheliaux  paradentaires").  The  central  epithelial  cells  being  cut 
off  from  their  blood  supply  die,  degenerate  and  liquefy,  and  a  cyst 
results. 

This  is  most  probably  the  correct  view. 


Fig.  232.  Fig.  233. 

Fig.  232. — Maxillary  non-carious  molar  having  a  large  dental  cyst  attached  to 
the  periodontal  membrane  of  the  buccal  roots.  It  became  displaced  during  the 
removal  of  the  tooth,  and,  rupturing,  its  contents  were  evacuated.  Mesial 
aspect. 

Fig.   233. — Same  as  the  preceding.      Buccal  aspect. 

A  dental  cyst  does  not  conform  at  all  closely  with  the  lines  of 
classification  enunciated  by  certain  general  pathologists.  In  the 
first  stage  of  its  evolution  it  is  not  derived  from  a  distension  of 
pre-existing  cavities  or  spaces  such  as  are  a  bursa,  a  ganglion,  a 
ranula,  a  galactocele;  it  is  not  a  cyst  of  new  formation,  like  an  ad- 
ventitious bursa,  a  haematoma,  a  proliferous  compound  cyst,  a 
parasitic  (hydatid)  or  an  implantation  cyst;  neither  is  it  of  congenital 
derivation,  as  is,  for  instance,  a  dermoid  cyst  or  a  cystic  lymphan- 
gioma.    The   important   point   to   emphasise   is   that  it  owes   its 

'  "Dental  Cysts,"  Journal  British  Denial  Association,  pp.  711,  et  seq.,  October, 
i8g8. 


26o   ,  -  THE    DENTAL    TISSUES 

being  to  an  infective  condition  of  the  tissue  in  which  it  is  found, 
whereas  none  of  the  cysts  enumerated  above  directly  does. 

It  has  recently  been  shown  ^  that  dental  cysts  are  not  entirely 
dependent  on  their  origin  on  teeth  with  septic  pulps,  as  in  the  in- 
structive case  referred  to  the  pulp  was  alive.  It  was  suggested  that 
it  was  the  outcome  of  spontaneous  growth  on  the  part  of  the  same 
epithelial  mass  or  masses.  In  the  ensuing  discussion,  Mr.  Turner 
expressed  the  opinion  that  it  might  have  arisen  in  connection  with  a 
neighbouring  tooth,  which  had  been  extracted  fifteen  years  previ- 
ously to  the  occurrence  of  the  cyst.  Incidentally  he  also  men- 
tioned that  a  cyst  may  originate  as  a  consequence  of  inflammation 
of  the  periodontal  membrane  due  to  "pyorrhoea  alveolaris." 

General  Characteristics. — For  a  classification  and  the  differential 
diagnosis  of  cysts  of  the  jaws,  see  Chap.  XV,  page  401. 

Macroscopical  Appearances. — On  their  facial  aspects  they  present 
a  smooth,  oval,  or  round  cystic  tumour  of  different  sizes  according 
to  the  stage  of  growth,  having  a  firm  but  elastic  capsule.  The  con- 
tents may  vary  from  a  yellow  thin  liquid  to  a  green  pultaceous 
substance. 

Secondary  Changes. — Inflammation  and  suppuration;  which  under 
suitable  conditions  may  lead  to  spontaneous  cure.  It  is  possible 
that  carcinomatous  degenerations  may  occur. 

HISTOLOGY 

A  dental  cyst,  after  evolving  from  a  solid  collection  of  epithelial 
cells,  consists  of  a  connective  tissue  capsule  or  wall  of  varying  degrees 
of  thickness,^  which  encloses  masses  of  epithelium. 

There  is  a  small  round-celled  infiltration  into  the  capsule,  which 
is  most  pronounced  hear  the  epithelial  lining.  Russell's  fuchsine 
bodies  are  sometimes  present. 

The  epithelium  may  vary  in  character  and  amount.  Thus  the 
cells  may  be  round  or  oval  with  flattened  nuclei,  or  columnar  with 
spherical  nuclei,  or  even  occasionally  ciliated.  The  presence  of  cilia 
has  been  demonstrated  by  Turner,  Baker^  and  Rothmann. 

1  Ernest  B.  Dowsett,  "Dental  Cyst  arising  from  the  root  of  a  living  tooth," 
Trans.  Odonto.  Soc.  of  Great  Britain,  Jan.,  1901. 

2  In  some  specimens  examined  by  the  author  it  was  3.25  mm.  in  width,  the  oral 
mucous  membrane  being  0.9  mm.  in  width. 

'  "Notes  on  the  Pathology  of  a  Dentigerous  Cyst,"  Dublin  Journal  0/  Medical 
Science,  October,  1891. 


DISEASES    or   THE   ALVEOLO-DENTAL   PERIOSTEUM  26 1 


Fig.   234. — Russell's  fuchsine  "bodies"  in  wall  of  a  dental  cyst.      Stained  with 
heematoxylene  and  fuchsine.      Magnified  250  times,     b.  "Bodies." 


Fig.  235. — The  interior  of  a  smnll  d'tiial  cy.st.  Stained  with  htematoxylene 
and  eosinc.  Magnified  45  times,  c.  Cystic  cavity;  E.  Epithelial  lining,  w. 
Cellular  infiltration  of  fibrous  tissue  of  wall  of  cyst. 


262 


THE    DENTAL    TISSUES 


As  regards  the  occurrence  of  ciliated  columnar  epithelium  in 
dental  cysts,  Turner  thinks  that  it  may  be  a  "reversion  to  type  or 
a  freak  of  growth,"  while  Baker  writes  as  follows: — 


Fig.  236. — A  section  through  the  entire  wall  of  a  dental  cyst.  Prepared  by 
fixing  and  hardening  in  formic  aldehyde  and  alcohol,  and  carefully  decalcifying 
in  a  weak  solution  of  hydrochloric  acid.  Stained  with  Ehrlich's  acid  heematoxy- 
lene,  counterstained  with  eosine.  Magnified  20  times.  o.E.  Oral  epithelium; 
G.  Gum  tissue;  p.  Periosteum  slightly  detached  from  surface  of  the  bony  wall; 
B.  Attenuated  bone;  c.w.  Wall  of  cyst;  e.  Epithelium;  f.s.  Inner  surface  of  cyst 
wall. 


"At  first  sight  it  seems  a  little  difficult  to  account  for  the  pres- 
ence of  columnar  epithelium  in  a  position  remote  from  the  respira- 
tory tract  and  those  other  places  where  it  is  usually  found:  still 
if  we  remember  the  way  in  which  ciliated  epithelium  is  regenerated, 
its  presence  in  my  case  will  not  be  quite  so  obscure.     It  is  a  well- 


DISEASES    OF   THE   ALVEOLO-DENTAL  PERICSTEUM  263 


CE 


cc 


o  s 


Fig.  237. — A  section  through  a  small  dental  cyst.  c.w.  Cyst  wall;  C.e. 
Ciliated  epithelial  lining;  c.c.  Cyst  cavity;  o.s.  External  surface  of  the  tumour; 
R.   Extremity  of  root  of  tooth.      {Prepared  and  photographed  by  A.  W.  W.  Baker.) 


C  K 


C  C 


CE 


Fig.   238. — ^A  portion  of  the  preceding.      More  highly  magnified.      c.E.   Ciliated 
epithelium;  c.i.   Cellular  infiltration;  c.c.    Cyst  cavity. 


264  THE    DENTAL    TISSUES 

known  experiment  that  when  the  ciHated  epithehum  is  artificially 
removed  from  a  portion  of  the  inner  surface  of  a  rabbit's  trachea, 
the  denuded  surface  speedily  becomes  again  covered  with  epithe- 
lium, which  grows  over  it  from  the  edge.  But  the  cells  form  at 
first  a  single  layer  of  flattened  epithelium;  they  next  acquire  ciHa, 
and  afterwards  become  columnar,  the  epithelium  thus  assuming 
the  character  which  it  has  normally  in  that  situation.  If  such 
transformations  are  possible,  there  is  no  reason  why  the  epithelium, 
which  is  frequently  present  in  the  root  membrane,  should  not  under 
suitable  conditions  become  changed  into  columnar  ciliated." 

In  amount  the  epithelium  is  sometimes  merely  a  thin  layer  of 
flattened  cells,  sometimes  a  thick  dense  collection  into  which  the 
sub-lying  tissues  send  papillary  eminences. 

Cholesterin,  which  is  a  monatomic  alcohol  and  soluble  in  ether, 
may  appear  in  the  fluid  contents  as  numerous,  flat,  minute,  rhomboi- 
dal  crystals  each  possessing  one  broken  corner. 

Tumours 

In  addition  to  the  cystic  tumour  already  noticed,  there  occa- 
sionally occur  homologous  neoplasms  which  belong  to  the  con- 
nective tissue  and  epithelial  groups  of  tumours  affecting  soft  tissues. 
This  is  not  surprising  when  the  histological  characteristics  of  the 
root  membrane  are  recollected.  Hence,  the  new  growths,  which 
are  not  due  merely  to  hypertrophy  of  soft  tissues  or  to  inflam- 
matory changes  within,  may  be  anatomically  classified  as: 

A.  Connective  tissue  tumours — 

1.  Tumours  of  the  type  of  fully-formed  connective  tis- 
sues, 

2.  Tumours  of  the  type  of  the  higher  connective  tissues, 

3.  Tumours  of  the  type  of  young  connective  tissue. 

B.  Epithehal  and  glandular  tumours. 

Of  these  main  divisions,  the  periodontal  membrane  possessesj 
as  far  as  investigations  go  at  present,  representative  growths  be- 
longing to  the  types  of 

1.  Fully-formed  connective  tissue,  e.g.  Fibromata, 

2.  Young  connective  tissue,  e.g.  Sarcomata,  and 

3.  Epithelial  tumours,  e.g.  Carcinomata. 


DISEASES    OF   THE   ALVEOLO-DENTAL  PERIOSTEUM  265 

I.  Fibroma 

The  macroscopical  appearances  of  this  benign  growth  arising 
from  the  periodontal  membrane  are  depicted  in  Figs.  239,  240, 
and  241. 

A  full  description  of  these  tumours  will  be  found  in  Chapter  XIII 


Fig.  239.  Fig.  240.  Fig.  241. 

Pig.  239. — Maxillary  right  first  incisor  with  fibroma  arising  from  the  perio- 
dontal membrane.      Distal  aspect. 

Fig.   240. — Same  as  preceding.     Labial  aspect. 
Fig.   241. — Same  as  preceding.      Mesial  aspect. 

2.  Sarcoma 

Oakley  Coles,  in  1885,  was  the  first  to  draw  attention  to  the  exist- 
ence of  round-celled  sarcoma  of  the  root  membrane,  the  diagnosis 
and  microscopical  examination  having  been  undertaken  by  Klein. 


Fig.  242.  Fig.  243.  Fig.  244. 

Fig.  242. — Round  celled  sarcoma  of  the  periodontal  membrane  beginning 
between  the  roots  of  a  non-carious  maxillary  molar.     Radicular  aspect. 

Fig.  243. — Another  non-carious  maxillary  molar  similarly  affected  to  that  in 
preceding  figure.     A  more  advanced  condition.      Radicular  aspect. 

FiG._  244. — Another  non-carious  maxillary  molar,  similarly  affected  to  that  in 
preceding  figure.     A  more  advanced  condition.     Radicular  aspect. 

And  the  author  has  observed  several  possible  cases.  There  is  some 
shadow  of  doubt  that  all  these  instances  are  true  sarcomata.  The 
close  approximation  of  appearances  presented  by  inflammation  of 
the  root  membrane,  makes  this  element  of  uncertainty.     But  it 


2  66  THE    DENTAL    TISSUES 

must  be  remembered  that  all  fibrous  tissues,  especially  those  of  the 
periosteum  of  bones,  have  a  special  predilection  to  undergo  sarco- 
matous changes;  and  the  clinical  histories  must  not  be  ignored. 

The  chief  points  of  interest  in  connection  with  these  periodontal 
tumours  lie  in  the  facts  that  they  are  found  in  connection  with  the 
roots  of  sound  teeth,  and  that  their  characteristics  are  those  of 
round-celled  (alveolar)  sarcomata. 

Seats  of  Occurrence. — In  half-a-dozen  cases  which  have  come  un- 
der the  immediate  observation  of  the  author,  each  growth  was  con- 
fined, as  its  locus  principii,  to  the  periosteum  of  the  molar  teeth, 
the  maxillary  being  much  oftener  affected  than  the  mandibular 
series.  It  was  generally  seen  to  rise  from  a  point  situated  at  the 
junction  of  the  roots  with  the  body  of  the  tooth;  but  it  may  have  its 
origin  from  the  sides  of  one  or  even  two  roots.  Later,  it  generally 
fills  up  the  whole  of  the  interradicular  region  of  the  tooth  (Fig. 
244). 

The  Etiology  of  the  disease  is  obscure;  but  there  seems  to  be  a 
predisposition  on  the  part  of  the  growths  to  attack  the  fibrous  mem- 
branes of  the  teeth  of  women  about  the  period  of  the  menopause. 
Long-continued  and  powerful  friction,  as  shown  by  the  wearing 
down  of  the  cusps,  is  possibly  the  exciting  cause. 

The  Subjective  symptoms  point  chiefly  to  long-continued  sharp 
pain,  increased  on  pressure,  the  course  of  the  disease  lasting  some- 
times several  months.  The  pain  is  severe  at  times,  and  such  as  to 
render  necessary  immediate  extraction  of  the  loosened  organ. 

Objective  Symptoms. — On  examining  the  mouth,  at  first  there  is 
sometimes  almost  entire  absence  of  swelling  or  of  any  of  the  usual 
inflammatory  signs,  and  the  tissues  are  not  markedly  indurated. 
There  may  be  slight  suppuration.  If  the  disease  is  not  far  ad- 
vanced, diagnosis  is  only  complete  after  the  removal  of  the  tooth. 
Later,  well-marked  symptoms  of  mahgnancy  appear. 

The  tumours  vary  in  size  from  a  split  pea  to  a  small  nut,  and 
have  a  smooth,  convoluted,  rarely  ragged,  surface.  They  are 
firm  to  the  touch,  and  are  of  a  deep  red  colour.  The  teeth 
themselves  are  non-carious,  and  exhibit  in  their  hard  parts  no 
traces  of  disease  except  some  attrition  of  their  cusps  and  (in  some 
cases)  absorption  of  the  apices  of  the  roots.  They  are  markedly 
loose,  and  signs  of  chronic  inflammation  of  the  periosteum,  accom- 
panied by  an  accumulation  of  tartar,  are  often  noticed. 


DISEASES    OF   THE   ALVEOLO-DENTAL   PERIOSTEUM 


267 


HISTOLOGY 

The  growths  consist  of  masses  of  cells  held  together  by  a  fine 
network  of  fibrous  tissues  which  is  very  dense  here  or  very  loose 
there,  and  is  in  some  places  apparently  undergoing  fibrification  or 
calcification.  In  the  centre  of  the  growth  this  network  is  scanty, 
but  the  intercellular  tissue  is  conspicuous  outside.  Vessels  are 
scanty  in  the  centre  and  have  extremely  thin  walls;  they  ramify 
among  the  cells.  In  the  outer  portion  they  are  larger  (but  not 
dilated)  and  have  normal  walls.     The  cells  themselves  are  for  the 


Fig.    245. — A  small  round-celled  sarcoma  of  the  periodontal  membrane, 
with  haematoxylene.      Magnified  750  times. 


Stained 


most  part  rounded  in  shape  and  considerably  larger  than  red  blood 
corpuscles.  They  contain  one  or  more  nuclei  and  are  devoid  of 
any  definite  cell  wall  (see  Fig.  245).  Great  numbers  of  spindle 
cells  exist.  There  is  little  haemorrhage  into  the  tissues,  proba- 
h)ly  because  of  the  small  size  of  the  growth,  and  because  it  has 
not  advanced  sufficiently  to  allow  of  large  haemorrhages  to  take 
place  in  its  substance;  but  small  extravasations  of  blood  corpuscles 
are  noticed  here  and  there.  Microscopically  the  growth  is  prac- 
tically indistinguishable  from  granulation  tissue;  considered  from  a 
clinical  aspect,  however,  there  can  be  no  doubt  as  to  its  malignant 
nature.     A  jaw,  excised  for  malignant  disease  of  the  antrum,  which 


205  THE    DENTAL    TISSUES 

is  now  in  the  possession  of  the  author  shows  unmistakable  signs 
of  the  sarcomatous  growth  beginning  in  the  root  membranes  of 
the  premolar  and  molar  series,  and  extending  into  the  floor  of  the 
antrum,  and  surrounding  alveolar  portions.  It  infected  the  soft 
tissues  very  thoroughly.  This  specimen  for  which  the  author  is 
indebted  to  his  friend  the  late  Mr.  W.  J.  Pilcher,  was  believed  by 
this  surgeon  to  originate  de  novo  in  the  root  membranes  of  the  teeth 
of  the  patient,  w^ho  was  a  young  male  adult  of  about  1 8  or  20  years. 

To  sum  up,  it  may  be  said  that  sarcomatous  disease  of  the  perio- 
dontal membrane  is  not  rare  in  its  earlier  forms,  but  that  it  is  very 
seldom  met  with  in  an  advanced  condition;  and  that  removal  of  the 
affected  tooth  fortunately  cuts  short  its  career  if  taken  sufiiciently 
early,  but  if  it  is  allowed  to  continue,  it  constitutes  another  starting- 
place  for  malignant  disease  of  the  maxillae. 

Less  malignant,  but  very  rare  also,  are  tumours  occasionally 
arising  from  the  periodontal  membrane,  which  exhibit  the  character- 
istic giant-cells  of  myeloid  sarcoma. 

They  will  be  more  fully  described  in  Chapter  XIII;  but  here  it 
may  be  said  that  while  they  present  on  the  gum  surface  as  a  so- 
called  myeloid  "epulis,"  they  have  sometimes  distinct  connections 
with  the  periosteum  of  the  roots  of  teeth. 

3.  Squamous  celled  carcinoma 

Epithelial  malignant  tumours  of  the  alveolo-dental  membrane  are 
very  rare.  But  their  rarity  in  no  way  detracts  from  the  importance 
of  their  early  diagnosis,  and  of  the  strictest  prophylactic  measures 
to  be  always  taken  with  regard  to  their  possible  source  of  future 
development. 

In  the  Trans.  Odonto.  Soc.  of  Great  Britain,  June,  1901,  and  under 
the  title  of  "A  Case  of  Burrowing  Epithelioma,"  Dr.  Stanley  Colyer 
has  succinctly  described  a  remarkable  illustration  of  this  affection. 
A  similar  case  of  "boring"  epithelioma  ("burrowing  carcinoma") 
had  previously  been  described  by  Sir  Henry  Butlin  {Pathological 
Trans,  vol.  xxxii,  212,  1881),  while  Reclus,  in  1876,  was  the  first 
to  note  and  record  the  condition.  This  is  not  the  place  for  full 
references  to  be  made  to  these  communications.  The  reader  is 
referred  to  the  pages  of  the  Transactions  (pp.  231  to  242),  for  Dr. 
Colyer's  statements. 

Nevertheless  the  writer  here  quoted  may  be  allowed  to  express 
his  opinion  as  to  the  possible  and  probable  etiology  of  cancer  of  the 


DISEASES    OF   THE   ALVEOLO-DENTAL  PERIOSTEUM 


269 


periodontal  membrane,  an  opinion  which,  it  may  be  added,  is  com- 
pletely endorsed  by  the  author. 

Etiology. — The  pathological  history  of  the  case  was  somewhat  as 
follows: — 

"The  pulp  was  infected  through  a  carious  cavity  and  died; 
it  then  set  up  a  suppurative  inflammation  around  the  apex.  The 
pus  pointed  and  left  behind  it  an  incurable  sinus  which  would  suggest 
— at  any  rate  after  the  tooth  had  been  sterihsed — that  some  portion 
of  the  tooth  was  necrosed.  The  necrosed  portion,  acting  as  an 
irritant,  would  cause  a  hypertrophy  of  the  stripped-up  pericementum 
and  a  proliferation  of  the  epithehum  therein.  The  pain,  though 
not  great,  would  put  the  tooth  out  of  use,  and  the  pericementum, 


Fig.  246.  Fig.  247.  Fig.  248.  Fig.  249. 

Fig.  246. — Squamous  celled  carcinoma  arising  from  the  periodontal  membrane 
of  a  maxillary  left  first  incisor.  The  apical  portion  of  the  root  was  much  ab- 
sorbed.    Labial  aspect. 

Fig.  247. — Squamous  celled  carcinoma  arising  from  the  periodontal  mem- 
brane of  a  maxillary  right  first  incisor.     Labial  aspect. 

Fig.  248. — Squamous  celled  carcinoma  arising  from  the  periodontal  mem- 
brane of  a  maxillary  left  canine.  Apical  portion  of  the  root  considerably  ab- 
sorbed.     Distal  aspect. 

Fig.  249. — Squamous  celled  carcinoma  arising  from  the  periodontal  mem- 
brane of  a  maxillary  left  premolar.      Mesial  aspect. 


which  .  .  was  not  thickened,  would  be  functionally  isolated.  We 
have,  therefore,  got  a  functionally  isolated  pericementum  in  an 
otherwise  healthy  body,  a  condition  which  is  analogous  to  the 
breast  and  uterus  about  the  time  of  the  menopause.  According 
to  this  theory,  then,  the  nice  balance  existing  between  the  cells  of 
the  pericementum  is  lost,  the  epithelium  reverts  to  its  ancestral  pow- 
ers of  division,  and  burrows  into  the  surrounding  tissues,  whose 
physiological  resistance  is  reduced;  and  thus  the  cancer  is  born." 
Macroscopical  Appearances. — There  is  practically  nothing  to  assist 
the  diagnosis  of  the  lesion  by  gross  examination.  A  soft  mass  of 
firm  consistency  arising  from  the  periodontal  membrane  of  a  "dead" 
tooth,  with  or  without  disease  of  the  cementum  and  dentine  may  be 


270 


THE    DENTAL    TISSUES 


chronic  inflammation,  a  dental  cyst  (in  incipient  stages),  a  localised 
and  circumscribed  abscess,  a  round-celled  sarcoma,  or  an  epithelioma. 
Histology  not  only  helps  the  differential  diagnosis,  but  serves  again, 
in  a  striking  manner,  to  emphasise  the  dangers  attendant  on  the 
kilhng  of  pulps  in  teeth,  and  the  subsequent  insufficient  cleansing 
of  the  pulp  canals.  It  must  never  be  forgotten  that  ''dead"  teeth, 
unless  they  have  undergone  a  rigorous  course  of  scientific  treatment, 
may  seriously  menace  the  health,  or  even  bring  about  the  death  of 
patients. 


C  N 


Fig.  250. — Epithelioma  of  the  periodontal  membrane  ("Burrowing  epithe- 
lioma"). Stained  with  Ehrlich's  acid  hsmatoxylene.  Magnified  230  times. 
C.N.  Cell-nest;  c.i.  Small  celled  infiltration  of  the  tissues;  e.  Island  of  epithelial 
cells. 


HISTOLOGY 


As  far  as  the  microscopical  appearances  of  the  specimens  under 
consideration  go,  it  is  unnecessary  to  detail  the  various  structures 
which  comprise  the  substance  of  the  growth.  Epitheliomata  agree 
in  all  essential  particulars  wherever  found.  For  a  description  of 
carcinomata  of  the  gums  and  palate,  the  reader  is  referred  to 
Chapter  XIII.  The  appended  photomicrograph  (Fig.  250)  gives 
the  general  appearances  of  such  a  specimen. 


CHAPTER  XI 
"PYORRHCEA  ALVEOLARIS" 

Introductory — The  gingival  margin — The  periodontal  membrane — The 
apical  region — The  cementum — The  bone  of  the  jaw — Conclusions — 
Normal  arrangements  of  the  osseous  and  fibrous  tissues — Early 
changes  producing  osseous  atrophy — Absorption  by  granulation 
tissue — Chronic  periostitis  and  senile  changes — "Pockets" — Ana- 
tomical and  clinical  observations — Summary. 

INTRODUCTORY 

The  oral  diseases  of  which  ''pyorrhoea  alveolaris"  is  a  symptom 
have  engaged  the  attention  of  many  observers  from  the  days  of  Fau- 
chard  in  1746  and  Jourdain  in  1778  to  the  present  time,  when,  more 
than  ever,  the  whole  of  the  medical  profession,  as  well  as  the  modern 
dental  surgeon,  has  become  acquainted  with  them  in  a  greater 
or  less  degree.  Next  to  dental  caries,  "pyorrhoea  alveolaris" 
has  especially  attracted  the  notice  of  dental  surgeons  on  account 
of  its  universality,  its  controversial  character,  its  obscure  etiology, 
its  occasional  difficulty  of  diagnosis,  its  recondite  morbid  anatomy, 
its  usual  intractability  to  treatment.  It  would  be  futile  and  dis- 
tinctly beyond  the  scope  of  this  chapter  to  review,  however  briefly, 
the  whole  field  of  literature  relating  to  it.  In  spite  of  all  that  has 
appeared  it  is  still  uncertain  as  to  whether  the  flo-wdng  of  pus  from 
the  alveolar  sockets  of  the  teeth  is  a  local  or  a  constitutional  symp- 
tom, or  both. 

Definition. — Literally — "A  flowing  of  alveolar  pus."  It  is  a 
symptom  or  sign  of  an  infective  condition  of  the  socket  or  sockets  of 
the  teeth.  Purulent  effusion  may  be  limited  to  one  tooth  or  may 
be  general.  It  may  exist  for  years  localised,  or  rapidly  spread.  It 
is  accompanied  by  a  slow  wasting  or  atrophy  of  the  alveolar  proc- 
esses of  the  jaws,  and  may  be  attended  by  the  formation  of  tartar, 
and  gradual  and  progressive  loosening  of  the  affected  teeth.  It  is 
generally  painless,  and  is  not  necessarily  inflammatory  in  origin 
or  in  consequence.  Chronic  inflammations  of  the  periodontal 
membrane  frequently  exist  without   "pyorrhoea."     Synonyms  are 

271 


272  THE    DENTAL    TISSUES 

numerous:  "Rigg's  disease,"  "interstitial  gingivitis,"  "hcemato- 
genic  calcic  pericementitis,"  so-called  "periodontal  disease,"  etc. 

Etiology. — Undetermined  at  present:  but  probably  constitutional 
diseases,  coupled  with  infection  of  the  gum  margins  with  pyogenic 
cocci,  may  briefly  be  considered  potent  factors  in  its  causation. 
Three  great  schools  of  thought  hold  conflicting  views  on  this  much- 
debated  question.  A  discussion  of  these  would  not  be  germane  to 
the  subject-matter  of  this  book.  Suffice  it  to  say  that  the  following, 
in  a  word,  represent  these  conceptions: — 

(i)  It  is  occasioned  solely  by  local  conditions  setting  up  inflamma- 
tion of  the  gums,  through  the  deposit  of  tartar,  etc.  A  belief  of 
Riggs  (Trans.  American  Academy,  1875),  Witzel  {British  Journal 
of  Denta;l  Science,  1882),  Black  ("American  System  of  Dentistry," 
1886), 

(ii)  It  is  due  to  bacterial  infection — opinions  of  Arkovy  ("Diag- 
nostik  der  Zahnkrankheiten,"  S.  232,  1885),  Galippe  ("Die  in- 
fectiose  arthro-dentare  gingivitis,"  1888),  and  Miller  ("Micro- 
organisms of  the  Human  Mouth,"  1890),  who  found  twenty- two 
varieties  of  bacteria  in  twenty-seven  different  cases, 

(iii)  And  finally,  it  has  been  ascribed  to  a  constitutional  origin 
such  as  gout,  rheumatism,  etc.,  theories  shared  alike  by  Tomes 
{op.  cit.),  Fitzgerald  {Clinical  Journal,  1899),  Pierce  {International 
Dental  Journal,  1892,  1894,  and  1895),  and  many  others  including 
Kirk,  Burchard,  and  Talbot  {" Interstitial  Gingivitis '''). 

Znamensky  of  the  University  of  Moscow,  with  the  assistance  of 
Dr.  Saricheff  and  Professor  Nikiforoff,  pubhshed  some  years  ago  a 
most  careful  paper  on  this  subject.  He  was  able  to  give  an  account 
of  the  microscopical  appearances  of  the  diseases  associated  with 
"pyorrhoea  alveolaris,"  for  he  had  obtained  sections  through  the 
teeth  and  jaws  of  a  woman  suffering  from  alveolar  "pyorrhoea,"  but 
who  had  died  from  another  disease.  This  is  described  in  the  later 
portions  of  this  chapter. 

The     author    has    had    the    opportunity    of    making    sections 

through  the  dental  and  alveolar  tissues  of  several  patients  who  had 

'pyorrhoea  alveolaris."^     In  this  chapter  he  proposes   to  put  on 

record  a  description  of  this  material,  with  the  conclusions  derived 

from  a  preliminary  study  of  them. 

The  first  specimen  was  the  right  maxilla  from  the  mouth  of  a 
male  twenty-eight  years  of  age.     Vertical  cuts  were  made  with  a 

^The  jaws  were  incised  after  death,  of  which  the  local  conditions  in  the 
mouth  were  no  contributory  cause. 


'PYORRHCEA   ALVEOLARIS 


273 


diamond  disk  through  the  can'ne  and  molar  teeth  and  an  interdental 
septum,  the  roots  of  the  molar  being  largely  exposed  on  both  the 


I    .^ 


B  ti'    .i..„ 


F      ^-. 


7'~ 


r 


-    c 


-     D 


/     '  ;•.  /• 


'  '1 


-  j''2m. 


Fig.  251. — Vertical  section  through  canine  and  right  maxilla  of  man  aged 
twenty-eight  showing  latest  stages  of  extremely  acute  conditions  associated  with 
"pyorrhoea  alveolaris."  Lateral  section,  a.  Apex  of  root  formed  by  hyperplasic 
cementum;  b.  Hyperplasic  periodontal  membrane;  c.  Indifferent  tissue  enor- 
mously increased  in  amount  and  more  vascular  than  usual;  d.  Soft  medullary 
tissue  exhibiting  signs  of  hyperplasia;  e.  Large  osteoporotic  space;  f.  Sequest- 
rum of  bone  undergoing  peripheral  absorption;  g.  Osteoclasts  producing  lacunar 
absorption  of  bone  of  socket;  H.  Bone  of  socket  partially  destroyed  and  converted 
into  osteoid  tissue;  i.  Line  of  junction  of  decalcified  and  normal  bone.  Mag- 
nified 35  times. 


labial  and  lingual  sides.     Macroscopic  examination  of  these  cuts 
showed  that  the  gingival  margin  in  the  canine  and  first  premolar 


274. 


THE    DENTAL    TISSUES 


region  was  greyish  in  colour,  believed  to  be  due  partly  to  blood-clot 
and  partly  to  the  presence  of  gangrenous  tissue.  The  teeth  were 
sound,  but  were  slightly  loose.  At  the  deepest  part  of  the  greyish 
area  a  somewhat  reddish  hne  was  observed,  forming  the  border  of 
demarcation  between  the  presumably  healthy  bone  of  the  jaw  and 
the  diseased  superficial  tissues.  The  first  of  these  pieces  was  rapidly 
decalcified  by  immersion  in  aqua  regia;  the  latter  were  treated  by  the 
Koch- Weil  method  of  Canada  balsam  impregnation. 


Fig.  252. — Free  margin  of  edge  of  socket  of  labial  surface  of  same.  a. 
Cementum;  b.  Inflamed  periodontal  membrane;  c.  Inflamed  gum  tissue;  d.  Free 
edge  of  bone  decalcified  and  converted  into  fibrous  intervening  tissue;  e.  Osteo- 
clasts producing  lacunar  absorption  of  external  and  internal  surfaces  of  bone. 
Magnified  80  times. 


The  second  specimen  was  a  portion  of  the  right  side  of  the  man- 
dible of  a  patient  of  thirty-nine  years,  extending  from  the  canine 
to  the  second  molar  inclusive.  The  second  maxillary  premolar  and 
first  molar  had  been  previously  extracted.  Two  vertical  incisions 
were  made  through  the  canine  and  bone,  and  one  on  the  mesial 
surface  of  the  root  of  the  second  molar.  The  canine  was  found  to 
have  undergone  attrition  and  was  non-carious.     A  slight  band  of 


"PYORRHCEA    ALVEOLARIS  275 

tartar  was  seen  on  the  lingual  surface.  This  was  treated  by  the 
Koch-Weil  process.  The  mass,  including  the  molar  root,  was 
decalcified. 

Another  specimen  consisted  of  the  right  maxilla  of  a  patient  of 
sixty  years,  from  the  canine  to  the  second  premolar  inclusive.  Two 
cuts  were  made  through  the  canine.  There  was  much  attrition 
of  this  tooth,  but  no  caries.  Tartar  was  present  on  the  labial  sur- 
face. One  piece  was  decalcified,  the  other  hardened,  after  staining 
en  masse,  in  balsam.  The  decalcified  sections  were  cut  on  an  ether- 
freezing  microtome  and  stained  with  Ehrhch's  acid  hajmatoxylene 
and  counter-stained  with  an  alcohoKc  solution  of  eosine  and  mounted 
in  Farrant's  medium,  as  less  hkely  to  cause  contraction  of  the  soft 
parts.  Some  sections  were  stained  by  Gram's  method  for  bacteria. 
The  Koch-Weil  specimens  were  stained  with  Grenacher's  alcohohc 
borax-carmine. 

More  material  was  examined,  but  it  is  unnecessary  to  give 
further  details. 

The  following  description  is  the  result  of  the  microscopical 
examination  of  tissues  profoundly  affected  by  acute,  later  phases 

of  the  condition. 

HISTOLOGY 

From  an  anatomical  point  of  view  this  may  be  conveniently  con- 
sidered under  the  following  headings:  (I)  The  gingival  margins. 
(II)  The  periodontal  membrane.  (Ill)  The  apical  region.  (IV) 
The  cementum.  (V)  The  bone  of  the  jaw.  This  is  of  course  an 
arbitrary  distinction,  but  it  serves  to  simplify  the  descriptions  of  the 

parts. 

The  Gingival  Margins 

The  oral  epithelium  is  apparently  altered  in  all  parts,  most  es- 
pecially at  the  periphery;  here  it  has  been  lost,  desquamation  having 
taken  place.  Nearest  the  free  edge,  the  cells  of  the  stratum  corneum 
and  lucidum  have  undergone  hydropic  degeneration.  Their  nuclei 
have  shrunken  and  many  are  moon-shaped  in  outline.  In  places 
where  the  epithehum  has  disappeared  the  papillary  eminences  of  the 
corium  remain  as  finger-like  processes  with  free  margins.  Through- 
out there  is  a  tendency  for  the  epitheUal  cells  to  become  confluent 
the  "spiny"  cells  so  commonly  found  in  normal  tissue  being  absent 
or  indistinguishable.  The  deeper  epithelial  cells  possess  small 
round  nuclei  and  are  greatly  increased  in  number,  showing  the 
phenomena  of  karyokinesis  very  markedly. 


276 


THE    DENTAL    TISSUES 


The  submucous  tissue,  consisting  usually  of  connective  tissue 
fibres,  is  everywhere  permeated  by  a  round-celled  infiltration,  as 
the  initial  stage  of  an  inflammation.  This  infiltration  is  most 
pronounced  in  the  papillae  of  that  part  of  the  gum  which  is  most 
closely  associated  with  the  necks  of  the  teeth.  A  "pocket"  has 
already  been  formed.     The  capillaries  are  hyperaemic  and  the  ducts 


__!     A 


Pig.  253. — Apical  region  of  same;  median  section,  a.  Apex  of  root  with 
hyperplasia  of  cementum;  b.  Hyperplasic  periodontal  membrane;  c.  Alveolar 
bone,  with  many  osteoporotic  spaces;  d.  Osteoclasts.      Magnified  35  times. 


of  the  gingival  glands  appear  swollen  and  more  prominent  than 
usual.  The  great  masses  of  inflammatory  cells  consist  of  crowds 
of  polymorpho-nuclear  neutrophiles,  eosinophiles,  lymphocytes,  and 
lymphoid  cells,  with  numerous  mast  cells  and  Unna's  plasma  cells. 
They  are  congregated  into  groups  or  clusters  between  the  fibres 


■PYORRHCEA   ALVEOLARIS ' 


277 


of  the  gum  tissue  and  of  the  periodontal  membrane,  which  are  all 
somewhat  coarser  than  usual. 

As    the    condition   advances   with    the   loss    of    the   epithelium, 
the  pathological  changes  are  exaggerated  to  such  a  degree  that  dis- 


if  -I 


l^'i _ 


\ 


""T 


±L 


Fig.  254. — Vertical  section  through  second  incisor  and  left  maxilla  of  woman 
aged  twenty-five.  Patient  unaffected  by  disease  of  the  bones.  No  "  pyorrhcea 
alveolaris  "  present.  For  purposes  of  comparison  with  Fig.  253.  a.  Apex  of 
normal  root;  b.  Normal  periodontal  membrane;  c.  Normal  alveolar  bone;  d. 
Normal  medullary  spaces  and  tissue.      Magnified  35  times. 

integration  and  death  of  cells  and  blood  corpuscles  has  taken  place, 
pus  cells  abound,  coagulation  necrosis  and  fatty  necrobiosis  of  super- 
ficial tissues  are  noted,  degenerative  lipogenesis  has  occurred,  and 
the  main  mass  has  become  necrotic  and  friable,  and  is  undergoing, 


278 


THE    DEXTAL    TISSUES 


most  superficially,  liquefaction,  due  most  probably  to  the  proteo- 
lytic ferments  as  well  as  to  the  enzymes  of  the  bacteria.  Huge 
colonies  of  micro-organisms  penetrate  the  tissues  from  the  surface 
and  can  be  seen  by  staining  with  gentian  aniline  violet — some  of  the 
masses,  however,  resisting  the  colouration  and  appearing  under  the 
1 6  mm.  objective  as  deeply  pigmented   spots  formed  at  the  free 


Fig.  255. — Vertical  section  through  another  part  of  canine  of  man  aged 
twenty-eight,  showing  destruction  of  socket.  -\.  Dentine  of  root;  B.  Pulp  canal; 
C.  Hyperplasic  cementum  at  apex;  d.  Hyperplasic  periodontal  membrane;  e. 
Inflamed  periodontal  membrane;  F.  Sequestrum;  G.  Bone  of  external  alveolar 
plate;  h.  Slightly  inflamed  gum  tissues;  I.  Bone  of  internal  alveolar  plate;  j. 
Osteoclasts  producing  lacunar  absorption;  K.  Osteoporotic  space;  L.  Osteoclasts 
producing  absorption  of  apex  of  root ;  m.  "  Gitter-figuren ; "  n.  Thrombosed  vessels 
in  periodontal  membrane;  o.  Decalcified  surface  of  G.      Magnified  35  times. 


edge  of  the  tissues.  The  inflammatory  cells  of  the  early  stages  have 
become  so  enormously  multipHed  that  the  nuclei  are  small  and  round, 
and  soon,  at  the  more  peripheral  parts,  pass  insensibly  into  the 
necrotic  tissue  just  mentioned,  which  stains  exceedingly  feebly 
and  almost  possesses  a  ground-glass-like  appearance,  traces  of  any 
structure  being  absent. 

But  these  intense  changes  are  secondary  to,  and  not  the  cause  of 
the  "pyorrhoea  alveolaris." 


'  PYORRHCEA    ALVEOLARIS ' 


279 


The  Periodontal  Membrane 

(a)  At  the  gingival  region:  Hyperasmia,  cellular  infiltration, 
hyperplasia  of  the  fibrous  elements,  increase  in  diameter  of  the 
membrane — these  are  the  most  prominent  features. 

Normally  measuring,  in  middle  age,  from  0.2  to  0.3  mm.  in  width, 
here  it  may  extend  to  the  enormous  width  of  i.o  mm.,  or  at  least 


Fig.    256. — Portion  of  same.     Lettering  as  in  preceding  figure. 
Magnified  30  times. 

0.8  or  0.9  mm.,  the  average  width  below  being  probably  about  0.6 
mm.  The  increase  in  thickness  is  obviously  due  to  the  absorption 
of  the  edge  of  the  alveolar  process,  which  normally  extends,  as  Zna- 
mensky  says,  "like  a  long  narrow  plate  not  containing  any  bone- 
marrow,"  of  "the  thickness  of  a  piece  of  paper." 

(b)  Lower  down,  that  is  at  the  cervical  region,  the  tissue  shows 
signs  of  a  slight  increase  in  its  cellular  elements  by  proliferation  of 


28o 


THE    DENTAL    TISSUES 


the  connective  tissue  cells.  There  is  no  great  amount  of  round- 
cell  infiltration  or  leucocytic  invasion.  In  places  it  is  not  greatly 
hyperaemic  and  the  tissue  fibres  are  not  well  marked.  Gland-like 
bodies  are  easily  seen,  but  are  not  enormous  nor  important.     But 


"     c 


Fig.  257. — Gum  tissue  over  external  alveolar  plate,  a.  Slight  depth  of 
"pocket";  b.  Gum  tissue  slightly  inflamed;  c.  Cementum;  d.  Normal  gum  tissue; 
E.  Osteoclasts  on  surface  of  external  alveolar  plate.      Magnified  80  times. 


probably,  taking  it  on  the  whole,  it  would  be  right  to  assume  that 
there  is  a  slight  congestion  of  the  soft  parts,  the  main  features  of 
which  are  masked  here  by  the  strong  fibrous  elements.  It  never 
amounts  to  a  general  periostitis  (periodontitis),  and  there  is  no 
granulation  tissue  present  except  in  very  advanced  conditions. 


■PYORRHCEA   ALVEOLARIS 


281 


The  Apical  Region 

This,  which  usually  measures  0.5  mm.  in  similar  specimens,  is 
now  twice  that  thickness,  filled  with  loosely  arranged  connective 
tissue  fibres  and  the  "indifferent  tissue"  of  Black.  Cells  and  blood- 
vessels (more  numerous  than  normally),  are  increased  in  numbers 
and  very  prominent  in  the  sections.  The  latter  frequently  branch 
and  are  filled  with  small  cells. 


\       G 


Fig.  258. — Lacunar  absorption  of  the  alveolar  bone  in  "pyorrhoea  alveolaris." 
Stained  with  haematoxylene.  a.  External  alveolar  plate  which  has  almost  become 
entirely  absorbed;  b.  Osteoclasts  on  surface  of  a;  c.  Hyperplasic  periodontal 
membrane;  d.  Thrombosed  blood-vessel;  e.  Normal  cementum;  f.  Dentine;  G. 
Hyperplasic  gingival  tissue.      Magnified  90  times. 


The  Cementum 


The  cementum,  generally  speaking,  is  hyperplasic,  but  not  mark- 
edly so.  Singularly  enough  its  peripheral  portions  are  remarkably 
smooth  and  well  defined,  and  seldom  exhibit,  except  at  the  apex 
of  the  teeth,  the  foveolae  of  Howship  occupied  by  large  myeloplaxes. 
If  it  is  at  all  hyperplasic  it  is  accidentally  so,  due  to  some  cause 
unassociated  with  the  "pyorrhoea  alveolaris." 

There  are  no  traces  of  bacterial  invasion  of  Sharpey's  fibres  and 
their  canals. 


2«2 


THE    DENTAL    TISSUES 


The  Bone  of  the  Jaw 

The  alveolar  bone  exhibits  even  before  the  gum  the  most  im- 
portant metamorphoses  which  have  occurred.  Briefly  they  are 
those  produced  by  the  process  of  halisteresis  (perhaps  a  form  of 


E     Z 


Fig.  259. — Free  margin  of  edge  of  internal  alveolar  plate.  A.  Cementum;  B. 
Inflamed  periodontal  membrane;  c.  Bone;  d.  Osteoporotic  space  with  inflamed 
medullary  tissue;  e.  Osteoclasts;  f.  Inflamed  gum  tissue;  g.  Masses  of  micro- 
organisms.     Magnified  35  times. 

osteomalacia).  Not  only  is  the  free  margin  of  the  bony  socket 
absorbed  by  osteoclasts  near  the  upper  and  lower  parts  of  the  cer- 
vical regions  of  the  teeth,  but  deep  down  at  the  radicular  portion, 
giving  the  surface  an  eroded  appearance;  moreover,  there  is  also  a 


•PYORRHCEA    ALVEOLARIS 


283 


decalcification  of  the  most  superficial  portions.  The  bone  becomes 
transformed  into  an  osteoid  tissue  through  loss  of  its  calcium  salts, 
then  passes  into  an  intervening  fibrous  tissue  and  finally  is  attacked 
by  the  inflammatory  exudation  and  cells,  its  bays  and  recesses  be- 
coming meanwhile  greatly  enlarged  and  filled  with  loose  soft  tissue, 
and  the  Haversian  canals  and  medullary  spaces  enlarged  and  irregu- 
lar, the  condition  being  termed  osteoporosis. 

Absorption  of  bone  may  occur  in  three  ways:  First,  by  the  ac- 
tivities of  the  osteoclasts  of  KoUiker  (myeloplaxes) ;  second,  by  the 


G     _ 


Fig.  260. — Another  portion  of  same.     Lettering  as  in  preceding  figure,     h.  Free 
surface  of  gum  from  which  the  oral  epithelium  has  become  desquamated. 


process  of  halisteresis;  third,  by  means  of  perforating  canals.  In 
the  case  of  diseases  such  as  give  rise  to  the  pathological  conditions 
here  studied,  the  two  former  are  plainly  going  on  side  by  side.  The 
first  is  well  understood.  The  second  process  may  be  described  as 
being  one  of  decalcification,  the  osseous  rtiatrix  appearing  as  osteoid 
tissue.  As  the  morbid  changes  progress,  the  osteoid  tissue  becomes 
more  fibrillated  than  usual,  and  finally  is  dissolved  and  incorpo- 
ratec]  in  the  medullary  tissue.  Frequently  are  seen  the  Gitter-figuren 
of  Von  Recklinghausen,  viz.,  variously  shaped  lines  or  markings  in 


284 


THE    DENTAL    TISSUES 


the  bone,   depending   upon  its   dissolution  by   the   decalcification 
agents  and  indicating  its  histodialysis  (Fig.  261). 

It  is  truly  remarkable  that  the  alveolar  portions  of  the  periodontal 
membrane  exhibit  numberless  osteoclasts  while  the  cemental  por- 
tion does  not.  It  is  therefore  probable  that  this  portion  of  the 
membrane  corresponds  to  the  inner  layer  of  the  periosteum  of  bones 
generally — the  proliferating  layer  of  Virchow  or  the  cambrium  of 


Fig.  261. — Another  portion  of  same.  a.  Cementuni;  b.  Bone;  c.  "  Gitter- 
figuren;"  d.  Inflamed  periodontal  membrane;  e.  Osteoclasts.  Magnified  250 
times. 

Billroth.  The  medullary  spaces  and  Haversian  canals  throughout 
the  sockets  of  the  teeth  are  osteoporous — that  is,  have  become 
eccentrically  atrophic — a  retrogressive  phenomenon  of  no  uncertain 
character.  The  same  changes  are  occurring  in  the  environment  of 
the  periodontal  membrane,  but  not  to  so  large  an  extent. 


CONCLUSIONS 


It  is  obvious  from  what  has  been  said  that  the  subject  is  vast, 
that  the  etiology  of  the  flowing  of  pus  from  the  sockets  of  the  teeth 
is  very  debatable,  and  its  pathology  little  understood.     The  author 


■PYORRHCEA   ALVEOLARIS' 


285 


ventures  to  state,  based  on  his  observations  of  the  microscopical 
appearance  of  sections  of  teeth  cut  in  situ  from  jaws  which  were 
distinctly  pyorrhoeic,  that — 


•  4-4 


it  9 


\      \ 


Fig.  262. — Vertical  section  through  canine  and  bone  of  right  side  of  mandible 
of  man  aged  thirty-nine.  "Pyorrhoea  alveolaris"  not  marked.  Tissues  over 
external  aspect,  a.  Dentine;  b.  Cementum;  c.  "Pocket"  of  gum,  the  edge 
of  which  is  attached  to  the  margin  of  cementum;  d.  Slight  desquamation  of  oral 
epithelium;  e.  SHght  inflammation  of  gum;  f.  Edge  of  alveolar  bone  transformed 
into  osteoid  tissue;  bone  lacunae  and  corpuscles  indistinguishable;  G.  Hyperplasic 
periodontal  membrane;  blood-vessels  injected;  H.  Normal  bone.  Magnified 
35  times. 


(ij  The  disease  of  the  bone  is  not  in  its  earlier  stages  a  rarefying 
osteitis.  According  to  the  most  eminent  authorities  osteitis  rare: 
faciens  is  '  characterized  by  the  development  of  vascular  granulation 


286 


THE    DENTAL    TISSUES 


tissue  of  the  medullary  spaces  and  canals,  associated  with  a  lacunar 
absorption  and  canahsation  of  bone,  which  becomes  porotic  and" 
soft."     (Hektoen     and    Riesman,    "A   Text-book   of    Pathology," 


Pig.  263. — Vertical  section  through  canine  and  socket  of  right  maxilla  of  man 
aged  sixty.  Tissues  over  internal  aspect,  a.  Dentine;  b.  Hyperplasic  cementum; 
c.  Bone  of  jaw;  no  lacunar  absorption,  slight  decalcification  of  free  edges;  D. 
Periodontal  membrane  hyper aemic  and  showing  signs  of  senile  changes;  e.  Slight 
"pocket"  at  gum  margin,  slight  gingivitis. 


1901;  see  also  "A  Manual  of  Pathology,"  Joseph  Coats,  1900;  "A 
System  of  Surgery,"  Sir  Frederick  Treves,  1895;  article  by  H.  H. 
Glutton,  "Fungating  Ostitis  {Ostitis  carnosa  vel  fungosa),"  Rind- 
fieisch's  "Manual  of  Pathological  Histology,"  1873;  and  "Rarefying 


■PYORRHCEA    ALVEOLARIS 


287 


Osteitis,"  in  "An  Introduction  to  Pathology  and  Morbid  Anatomy," 
Henry  Green,  1895.) 

(2)  "Pyorrhoea  alveolaris"  does  not  begin  as  a  gingivitis. 


f:/^- 


*», 


•n-* 


-M'^ 


^  ' 


,i<  jjjjjifr  'xli^joi^ 


Fig.  264. — Same  as  before.  Apical  region  of  root.  a.  Dentine  of  root;  b. 
Indifferent  tissue  enormously  hyperplasia;  c.  Osteoporotic  bone.  It  will  be 
noticed  that  there  is  no  osteoporosis  at  present  at  cervical  region.  (See  pre- 
ceding figure.) 

(l)  It  is  essentially  dependent  upon  an  osseous  lesion,  an  atrophy 
0]  the  bone,  which,  in  the  thinnest  parts,  causes  the  cervical  margins 
of  the  teeth  to  become  denuded  through  the  halisteresis  and  osteo- 
clastic absorption. 

(4)  The  pus  associated  with  it  is  derived  from  debris  of  food, 


THE    DENTAL    TISSUES 


pyogenic  bacteria,  and  other  extraneous  elements,  which,  gathering 
in  the  wide  pockets  produced  by  the  atrophy  of  the  bone,  may  or 
may  not  set  up  ultimately  a  suppurative  gingivitis. 


Fig.  265. — Vertical  section  through  cervical  region  of  molar  of  man,  age 
unknown,  which  presented  no  symptoms  of  "pyorrhoea  alveolaris."  For  purposes 
of  comparison  with  the  foregoing,  and  to  demonstrate  the  fact  that  decalci- 
fication of  edge  of  alveolar  bone  may  exist  before  "pyorrhoea"  sets  in.  a.  Dentine; 
B.  Cementum;  c.  Hyperplasic  periodontal  membrane;  d.  Gum  tissue  with  deep 
gingival  trough  (nopus  present);  e.  Normal  gum;  f.  Decalcification  of  socket, 
no  lacunar  absorption.      Magnified  35  times. 

(5)  The  presence  of  calculus  is  not  sufficient  in  itself  to  induce  the 
condition,  and  may  not  be  associated  with  it  at  all  as  a  predisposing 
or  exciting  cause. 

(6)  Many  cases  of  pus  flowing  from  the  sockets  of  teeth  are  not 


■PYORRHCEA    ALVEOLARIS' 


289 


"pyorrhoea  alveolaris,"  but  are  frequently  incorrectly  described  as 
such. 

With  regard  to  the  statement  made  under  clause  (3)  it  seems  im- 
possible to  imagine  that  if  the  gingivitis  was,  alone  or  combined 
with  tartar,  responsible  for  the  pathological  conditions,  there  could 
be  no  alteration  in  the  bone  at  the  apices  of  the  roots,  or  in  situations 
far  removed  from  the  surface  of  the  gum.     But  this  occurs;  and  it  is 


a: 


-vNTf  -' 


^ 


Fig.  266. — The  same;  shows  tissues  over  internal  alveolar  plate,  a.  Cemen- 
tum;  B.  Normal  periodontal  membrane;  c.  "  Gitter-figuren;"  d.  Normal  bone; 
E.  Areas  of  decalcification.      Magnified  250  times. 

believed  that  the  gingivitis,  if  present,  is  secondarily  induced,  and 
that  this  gingivitis  is  produced  apart  from  the  bony  lesion  by  haema- 
togenous  infection  by  pus-producing  micro-organisms,  which,  how- 
ever, have  a  very  circumscribed  area  of  development. 


NORMAL   ARRANGEMENTS    OF   THE    OSSEOUS    AND   FIBROUS    TISSUES 

Examination  of  sections  of  the  teeth  in  situ  in  the  jaws  of  a  woman 
of  twenty-five  years,  whose  mouth  was  free  from  any  symptoms  of 


2go 


THE    DENTAL    TISSUES 


disease,  discloses  the  fact  (Figs.  267  and  268)  that  the  alveolar  proc- 
esses vary  in  thickness,  the  bone  being  very  narrow  at  the  gingival 
region,  broader  at  the  cervical  region,  while  narrowing  down  again 
at  the  radicular  portion  of  the  teeth  to,  roughly,  about  the  same 
diameter  as  in  the  first-named  situation.     At  the  apices  of  the  roots 


_,     A 


Fig.  267. — Normal  bone,  internal  alveolar  process,  from  jaw  of  woman  of 
twenty-five.  a.  Dentine;  b.  Periodontal  membrane;  c.  Normal  bone.  Magni- 
fied 80  times. 


the  bony  socket  is  closely  approximated  to  the  teeth  themselves, 
the  periodontal  membrane  undergoing  only  very  slight  enlargement, 
its  width  remaining  practically  the  same  throughout  its  whole 
extent.     The  fibres  of  the  gum  around  the  necks  of  the  teeth  are  not 


■PYORRHCEA    ALVEOLARIS 


291 


as  densely  arranged  as  one  would  expect  from  the  statements  of 
text-books.  In  no  sense  do  they  form  a  firm  annular  ligament,  as 
described  by  Stohr,  binding  the  soft  tissues  down  to  the  hard  parts. 
Indeed,  a  V-shaped  space  probably  always  exists  to  a  slight  degree 
in   normal   circumstances.     All  human   teeth   possess   spaces — the 


Fig.   268. — Same   as  preceding  illustration,  but  at  cervical  region.      Normal. 
Magriified  80  times. 

gingival  troughs — around  their  necks,  which  may  become  potential 
cavities  for  the  retention  of  micro-organisms  (see  Chapter  X,  Vol.  I). 
If  great  care  be  exercised  in  the  laboratory  manipulations,  it  will 
be  found  that  micro-organisms  can  always  be  demonstrated,  in 
ordinary  circumstances,  occupying  the  site  thus  produced.     It  is 


292  THE    DENTAL    TISSUES 

when  they  are  of  the  pus-producing  varieties  that  "pyorrhoea  alveo- 
laris"  is  estabhshed. 


EARLY   UNSUSPECTED   CHANGES   PRODUCING    OSSEOUS    ATROPHY 

In  the  mouths  of  people  of  middle  age  a  startling  fact  may  be 
frequently  observed.  Without  any  signs  of  gingivitis  whatever, 
or  the  presence  of  tartar  or  "pyorrhoea,"  when  the  gum  tissues  are 
what  one  would  call  normal  and  healthy  and  the  adjacent  teeth 
fully  functional  and  free  from  caries,  decalcification  or  halisteresis 
of  the  free  edge  of  the  osseous  socket  may  be  beginning  (see  photo- 
micrograph, Fig.  269).'  It  must  be  remembered  that  the  bone 
forming  the  dental  sockets  is  peripheral,  and — as  is  pointed  out  by 
the  author  in  Vol.  I — is  structurally  different  from  compact  bone, 
properly  formed,  elsewhere.  This  ill-constructed  attachment  and 
foundation  of  the  teeth  easily  and  early  falls  a  prey  to  disturbances 
in  the  vascular  system  of  the  jaws,  and  soon  begins  to  degenerate 
and  atrophy,  after  an  acute  attack  of  anaemia,  long-continued  fevers, 
rheumatism,  hydrargyrism,  etc. 

Investigated  by  the  author  was  an  affection  of  the  mandibular 
teeth  of  a  girl  of  ten  years,  who  suffered  from  osseous  atrophy 
associated  for  a  few  months  with  "pyorrhoea,"  which  resulted  in  a 
permanent  loosening  of  the  two  first  incisors.  The  rest  of  the  mouth 
was  healthy.  There  occurred  the  loss  of  the  bone  of  the  sockets, 
and  the  presence  of  extremely  deep  pockets  around  each  tooth.  The 
author  attributes  the  affection  in  this  case  directly  and  entirely  to  an 
acute  attack  of  anaemia,  following  chickenpox  at  three-and-a-half 
years,  which,  in  addition  to  producing  general  symptoms,  acted 
locally  by  modifying  the  usual  amount  and  character  of  the  blood 
supply  to  the  parts  and  causing  malnutrition  and  degeneration  or 
atrophy.  The  limitation  of  the  condition  to  the  two  teeth  named 
was  probably  owing  to  an  undue  amount  of  function,  the  posterior 
teeth  not  having  erupted.  Accentuated  use  is  as  bad  for  the  teeth 
as  is  idleness.  "Pyorrhoea  alveolaris"  may  be  confined  to  one  or 
two  teeth,  when  it  will  generally  be  found  that  they  are  either 
used  too  much — as,  for  instance,  in  holding  a  pipe  between  them 
— or  to  loss  of  function,  as  in  the  case  of  absence  of  an  opponent 
in  the  other  jaw. 

Sections  of  jaws  with  the  teeth  in  situ  which  would  be  considered 
as  normal,  very  frequently  exhibit  this  atrophy  of  the  bone.  The 
result  is  a  deepening  and  a  widening  of  the  gingival  trough  and  its 


■  PYORRHCEA   ALVEOLARIS ' 


293 


«fi 


.-'VJ 


i4*'f . 


Fig.  269. — Vertical  section  through  cervical  region  of  molar  of  man,  which 
presented  no  symptoms  of  "pyorrhoea  alveolaris."  a,  Cementum;  B.  Normal 
periodontal  membrane;  c.  "Gitter-figuren;"  D.  Normal  bone;  E.  Areas  of  decalci- 
fication.     Magnified  350  times. 


294 


THE   DENTAL   TISSUES 


transformation  into  a  pocket,  in  which,  if  pyogenic  bacteria  happen 
to  collect  and  develop,  "pyorrhoea  alveolaris"  is  bound  to  ensue. 


Fig.  270. — Mandibular  molar  showing  absorption  of  one  of  its  roots  by  means 
of  granulation  tissue  developed  as  a  consequence  of  chronic  inflammation  of  the 
periodontal  membrane.      (See  Fig.  271.) 


ABSORPTION   BY    GRANULATION   TISSUE 

In  order  to  further  test  the  statement  that  granulation  tissue — • 
a  part  of  osteitis  rarefaciens — is  not  present  in  the  earlier  conditions, 
a  lower  permanent  molar,  with  one  root  absorbed  as  a  result  of  the 


Fig.   271. — Granulation  tissue  absorbing  dentine. 

action  of  certain  cells  in  the  granulation  tissue  produced  by  an  in- 
flammation of  the  periodontal  membrane,  was  examined,  with  the 
microscopical  appearances  revealed  in  Fig.  271. 

It   is   important    to   recognise    the  fact  that  granulation  tissue 


PYORRHCEA    ALVEOLARIS 


295 


such  as  occurs  in  the  heahng  of  a  suppurating  wound,  consists  of  a 
dense  cellular  new  growth  freely  supplied  with  blood  from  capillary 
vessels  of  new  formation.  The  cellular  elements  comprise:  (a) 
Formative  cells  derived  from  pre-existing  cells  of  varying  shape  and 
size;  they  may  be  oval,  branched,  or  oat-like;  their  nuclei  round  or 
oval.  (6)  Polymorphonuclear  leucocytes,  which  take  no  part  in  the 
formation  of  the  new  tissue,  (c)  Small  lymphocytes  and  plasma  cells 
with  large,  round,  deeply  staining  nuclei,  (d)  Large  mononuclear 
hyaline  leucocytes,  which,  according  to  Metchnikoff,  have  the  prop- 


rT 


IT 


■^mmm:d 


-'  ii 


Fig.  272. — For  comparison.  Radicular  portion  of  firm  canine,  in  maxilla  of 
man  aged  forty-five.  a.  Hyperplasic  cementum;  b.  Periodontal  membrane. 
Magnified  40  times. 

erty  of  becoming  metamorphosed  into  connective  tissue  cells. 
(e)  Multinuclear  giant  cells.  The  latter  occur  in  granulation  tissue 
of  bacterial  origin  (like  tubercle),  and  in  "wounds,  around  necrotic 
material,  and  about  foreign  bodies."  In  the  photomicrograph  the 
latter  are  absent.  Comparison  of  this  figure  with  Figs.  263  and  264 
shows  the  difference  between  the  two,  and  demonstrates  the  fact 
that  no  granulation  tissue  is  present  in  the  sockets  of  teeth  in  the 
earlier  stages  of  "pyorrhcxia  alveolaris,"  and  does  not  necessarily 
always  exist  even  in  later  stages. 


296 


THE    DENTAL    TISSUES 


COMPARISON  BETWEEN   CHRONIC   PERIOSTITIS   AND    SENILE 
CHANGES 

Sections  were  cut,  for  further  comparison,  of  the  jaw  of  a  male  aged 
forty-five,  in  which  the  maxillary  left  permanent  canine  was  firm, 
and  its  distal  neighbour,  the  left  first  premolar,  was  extremely 
loose.  This  gave  an  opportunity  for  observing  the  differences  in 
the  microscopical  appearances  between  the  two  sockets,  the  former 
exhibiting  the  usual  degenerative  changes  of  the  periodontal  mem- 
brane which  are  incidental  to  middle  age,  and  the  other  the  abnormal 


•^  ^v 


-1 


' 


L 


2L L. 


Pig.  273. — For  comparison  with  preceding  illustration,  a.  Hyperplasic 
cementum;  B.  Chronic  inflammation  of  periodontal  membrane;  c.  Fracture  of 
cementum  mentioned  in  text.      Magnified  40  times. 

changes  due  to  chronic  periostitis  (periodontitis).  In  the  former 
there  are  no  signs  of  inflammation;  the  connective  tissue  is  increased 
in  amount,  and  is  more  pronounced  than  in  younger  membranes; 
in  the  latter,  all  the  histological  signs  of  chronic  inflammation  are 
seen.  But  there  is  a  marked  variation  from  those  of  "pyorrhoea 
alveolaris."  While  the  membrane  is  extremely  broad,  the  myeloid 
cells  and  osteoporous  spaces  of  the  bone  are  wanting      Incidentally 


"PYORRHCEA   ALVEOLARIS  297 

these  sections  also  show  the  fracture  of  an  extremely  minute  portion 
of  the  cementum  of  the  premolar. 

"pockets" 

In  Fig.  262  it  will  be  noticed  that  the  free  edge  of  the  gingival 
tissue,  as   represented  by  the  oral  epithelium,  is  loosely  adherent 
to  the  terminal  margin  of  the  cementum;  this  is  exhibited  under  a 
higher  magnification  in  Fig.  274.     The  enamel  has  been  lost,  owing 
to  decalcification  in  weak  aqua  regia.     No  hard-and-fast  rule  exists 
as  to  the  cervical  attachment  of  the  gum  tissues  from  an  anatomical 
point  of  view.     Even  as  the  normal  relationships  of  enamel,  dentine, 
and  cementum  vary,  so  do  the  attachments  of  the  soft  parts.     The 
"pocket"  in  this  section  is  extremely  slight;  nevertheless,  it  had 
contained,  during  the  life  of  the  patient,  a  mass  of  micro-organisms, 
which  had  induced  a  slight  suppurative  gingivitis  (e  in  Fig.  262),  and 
"pyorrhoea"  was  actually  present.     At  some  considerable  distance 
nearer  the  radicular  region  of  the  tooth,  the  usual  transformation  of 
the  periphery  of  the  alveolar  process  of  the  jaw  had  already  taken 
place,  the  bone  being  converted  into  osteoid  tissue  through  halistere- 
sis,  although  the  patient  was  only  thirty-nine  years  of  age.     This 
osseous  surface  was  extensively  decalcified  by  a  similar  process,  and 
the  blood-vessels  in  the  periodontal  membrane,  exercising  a  protect- 
ive influence,  were  hyperaemic.    When  this  is  compared  with  Fig.  265, 
in  which  case  "pyorrhoea"  was  absent,  it  is  found  that  in  the  latter 
a  deep  and  extensive  pocket  had  been  produced,  the  gum  margin 
being  attached  to  the  cementum  at  a  distance  of  1.5  mm.  below  its 
free  edge  (see  Figs.  275  and  276).     It  is  not  surprising,  therefore, 
that  a  small-celled  infiltration — which  is  a  normal  condition  of  the 
gum — has  occurred  in  the  immediate  neighbourhood  of  the  deep 
socket.     But  it  is  an  astonishing  fact  that  there  is  less  pathological 
decalcification  of  the  bone  than  in  the  preceding  instance,  clearly 
demonstrating  that  the  amount  of  loss  of  the  marginal  bone  does 
not  depend  upon  the  depth  or  shallowness  of  the  pocket.     It  is 
important    to    recall    that    here    no    "pyorrhoea"    whatever   was 
manifest. 

It  is  unnecessary  to  lay  before  the  reader,  at  present,  any  further 
histological  details,  but  in  support  of  his  views,  the  author  desires 
to  add  a  note  regarding  the  anatomical  and  chnical  aspects  of  the 
subject. 


298 


THE   DENTAL   TISSUES 


Fig.  274. — Same  as  Fig.  262.  A.  Free  edge  of  cementum;  b.  Oral  epithelium 
of  gum  tissue.  Above  A  is  a  shallow  pocket  filled  with  pus  during  life.  Mag- 
nified 350  times. 


PYORRHCEA    ALVEOLARIS" 


299 


Fig.   275.— Same    as  Fig.   265.      No  pus  present,      a.   Free  edge  of  cementum. 
Gum  tissue  adherent  below.      Magnified  350  times.      (See  next  figure.) 


300 


THE    DENTAL    TISSUES 


Fig.   276. — Same  as  preceding  illustration.      Gum  tissue  attached  to  cementum 
at  A.      Magnified  350  times. 


PYORRHCEA  ALVEOLARIS  301 

ANATOMICAL   AND   CLINICAL    OBSERVATIONS 

Absorption  of  each  alveolar  process  of  the  jaws  is  a  common 
occurrence;  it  is  the  rule  in  man  and  the  lower  animals.^  The  more 
aged  the  individual  the  greater  the  loss  of  this  bone,  with  the  con- 
comitant shedding  of  its  dental  occupants.  The  teeth  of  dogs,  cats, 
monkeys,  and  other  animals,  either  in  a  domesticated  environment 
or  in  naturd  /era,  become  loose  as  time  passes  by,  as  a  direct  con- 
sequence of  the  absorption  of  their  sockets — a  physiological  process. 
Man  becomes  more  and  more  inclined  to  be  edentulous  as  he 
advances  in  life,  a  part  of  the  decadence  of  his  vital  powers.  Thou- 
sands of  skulls  of  aged  people  exist  where  the  teeth  remain  in  situ. 
This  is  due  to  the  splendid  natural  physique  of  the  owners.  But 
in  probably  eighty  per  cent,  of  individuals  living  in  highly  civilised 
communities,  it  is  the  normal  condition  for  the  alveolar  processes 
to  atrophy  and  shrink,  for  the  gum  tissues  to  become  thinner  and 
degenerate,  and  for  the  roots  of  the  teeth  to  become  exposed. 
Many  cases  of  so-called  "periodontal  disease"  are  not  the  outcome 
of  pathological  disturbances  at  all,  hence  it  follows  that  these  senile 
changes,  which  may  begin  early  or  late  in  life,  may  induce,  in  the 
first  instance,  the  deepening  and  widening  of  the  normal  trough  at 
the  gum  margin,  and  then,  if  this  is  infected  by  pyogenic  bacteria, 
"pyorrhoea  alveolaris"  follows.  Clinically,  "pyorrhoea"  is  un- 
accompanied by  pain,  i.e.,  generally  speaking;  if  complications  exist, 
pain  may  be  present.  As  a  rule,  its  evidences  and  effects  are  un- 
known to  the  patient,  and  its  diagnosis,  at  times,  is  difficult  for  the 
dental  surgeon.  If  it  were  produced  by  an  osteitis  rarefaciens,  as 
is  so  generally  believed,  it  is  more  than  likely  that  all  the  signs  and 
symptoms,  objective  as  well  as  subjective,  of  chronic  periostitis 
would  supervene,  and  the  patient  would  be  duly  warned.  But 
this  is  not  so. 

From  his  personal  experience  of  cases  in  which  "pyorrhoea 
alveolaris"  was  a  prominent  symptom,  the  author  is  led  to  the  con- 
clusion that  the  morbid  conditions  of  the  jaws  which  produce  the 
flowing  of  pus  are  not  the  etiological  factors  of  severe  metabolic 
disturbances  of  the  alimentary  tract  or  the  vascular  system,  but 
that  they  are  part  and  parcel  of  them.  A  strong  infection  of  the 
oral  cavity  by  means  of  pathogenic  micro-organisms  may  induce 
both  an  extensive  "pyorrhoea"  in  the  pockets  already  deep  enough 
to  receive  them,  in  all  parts  of  the  mouth,  and  contemporaneously 

1  See  Appendix,  Vol.  I. 


302 


THE    DENTAL    TISSUES 


a  secondary  toxaemia  or  other  lesion  which  reacts  universally  on 
the  bodily  tissues.  "Pyorrhoea  alveolaris"  does  not  initiate  but  is 
produced  by  the  same  septic  cause  which  leads  to  general  systemic 
affections,  and  which  may  set  up  among  other  diseases  alimentary 
toxaemia,  gastritis,  enteritis,  chronic  toxaemia,  chronic  rheumatism 
and — remotely — septic  anaemia,  pernicious  anaemia,  arthritis,  endo- 
carditis, septicemia,  etc. 

SUMMARY 

To  sum  up.     The  course  of  events,  in  the  opinion  of  the  author, 
is  as  follows:  Atrophy  of  the  bony  socket  and  shrinkage  is  followed 


EC  v^ 


H  F 


-—-7  K    -ST-vAW 

F  D  IP  -S^Xi^, 


O  T- 


B  V 


r. O 


Fig.   277.  Fig.   278. 

Fig.  277. — The  gum  and  surrounding  structures  in  "pyorrhoea  alveolaris."' 
Magnified  80  times,  d.  Dentine;  c.  Cementum;  p.m.  Root  membrane;  g.  Normal 
tissue  of  the  gum;  B.  Normal  bone;  o.e.  Oral  epithelium;  e.g.  Dead  epithelium 
cells  being  cast  off  the  ulcerated  surface  of  gum;  t.  Tartar  at  gingival  margin; 
I. p.  Inflammatory  cells  and  products.  (After  Znamensky,  from  the  Journal  of 
the  British  Dental  Association.) 

Fig.  278. — Same  as  the  preceding,  and  from  the  same  source.  Magnified 
180  times.  Lettering  as  before,  but  also — o.T.  Outer  part  of  socket  being  trans- 
formed into  osteoid  tissue;  h.f.  Howship'sfoveolce  on  inside  portion;  o.  Osteoclast; 
B.v.   Capillary  in  normal  root  membrane. 


by  a  widening  of  the  gingival  margin  and  broadening  and  deepening 
of  the  troughs,  with  hyperplasia  of  the  periodontal  membrane.  If 
a  pathogenic  infection  occurs,  there  is  a  lodgment  of  pyogenic 
bacteria  in  these  already  suitable  pockets,  and  "pyorrhoea"  results, 
and  it  may  or  may  not  be  accompanied  by  gingivitis  and  the  produc- 
tion of  tartar. 


"PYORRHCEA    ALVEOLARIS  303 

znamensky's  researches 

Znamensky^  sums  up  his  opinions  as  follows: — 

1.  The  process  in  the  bone  is  osteitis  rarefaciens. 

2.  The  disease  develops  not  primarily  in  the  bone,  but  begins 
with  a  suppurative  inflammation  of  the  gums,  which,  approaching 
the  bone,  gradually  produces  therein  the  above-mentioned  condition. 

3.  An  osteoporous  form  of  atrophy  of  the  sockets  affords  a  very 
favourable  nidus  for  its  development. 

4.  Exhausting  diseases  create  in  the  alveolar  sockets  a  favourable 
nidus  for  the  development  therein  of  "pyorrhoea  alveolaris"  in  the 
form  of  an  osteoporous  atrophy. 

5.  The  lack  of  real  hygienic  care  in  regard  to  the  teeth  at  the  time 
of  the  foregoing  constitutional  diseases,  and  a  deposition  of  tartar 
give  rise  to  a  suppurative  inflammation  of  the  gums,  which  rapidly 
passes  into  "pyorrhoea"  on  the  suitably  prepared  nidus  of  the  bone 
of  the  sockets. 

6.  In  slight  cases,  affecting  only  that  part  of  the  socket  which 
does  not  contain  bone-marrow,  the  hygienic  care  of  the  teeth — 
such  as  removal  of  tartar,  washing  with  disinfectant  and  astringent 
lotions,  and  correct  regimen  of  diet  will  alone  be  sufficient  to  suppress 
the  ailment.  In  severe  cases  more  stringent  and  radical  measures 
must  be  adopted. 

HISTOLOGY    (zNAMENSKY) 

First  steps.  Irritation  of  the  gums  occurs  through  depositions 
of  tartar,  occupying  the  normal  gingival  margins.  A  very  hard 
swollen  rim  of  gum  appears  strongly  infiltrated  with  leucocytes. 
It  includes  the  papillary  layer  of  the  gum,  the  alveolar  socket  being 
at  first  unaffected.  Soon  the  gum  loses  its  superficial  epithelium, 
and  an  ulcerated  surface  results.  Emigration  of  leucocytes  from  the 
vessels  takes  place  (see  Fig.  277). 

On  reaching  the  thin  edge  of  bone  (which  in  this  situation  does 
not  possess  any  large  medullary  spaces,  and  therefore  no  marrow) 
inflammatory  changes  at  once  begin.  On  its  free  rim,  which  here 
attains  only  the  thickness  of  a  sheet  of  note  paper,  the  socket  loses 
lime  salts,  and  undergoes  transformation  into  an  osteoid  tissue, 
and  afterwards  into  a  fibrous  intervening   (uniting)   tissue.     This 

1  "Alveolar  Pyorrha-a — its  Pathological  Anatomy,  and  its  Radical  Treat- 
ment." Journal  Brit.  Dent.  As.'soc,  October,  1902.  Also  Trans.  Int.  Med. 
Congress,   ic)iZ- 


304  THE    DENTAL    TISSUES 

loss  of  lime  salts  is  shown  by  the  homogeneous  character  of  the  bone, 
absence  of  lamellae,  and  loss  of  the  characteristic  outhnes  of  the  bone 
lacunae  and  canahcuh.  This  part  is  separated  by  a  hne  of  demarca- 
tion from  the  healthy  part.  This  portion  of  the  bony  socket  is 
thus  transformed  into  a  fibrous  tissue,  which  passes  more  deeply 
into  an  osteoid  tissue,  which  ultimately  absorbs  the  thin  bony  plate 
of  the  alveolar  septum. 

At  this  stage  the  periodontal  membrane  begins  to  be  affected. 
Its  blood-vessels  are  much  dilated,  and  leucocytes  immigrate  in  all 
directions. 

Destruction  and  removal  of  the  thinnest  portion  of  the  alveolar 
plate  are  brought  about  thus:  Under  the  influence  of  the  external 
inflammation  of  the  gum  the  bone  becomes  decalcified,  then  trans- 
formed into  an  osteoid  tissue,  and  afterwards  into  a  fibrous  tissue, 
which  is  soon  thoroughly  infiltrated  with  leucocytes. 


s  — - 


Fig.  279. — The  final  stage  in  the  development  of  "pyorrhoea  alveolaris." 
From  the  same  source.  Magnified  360  times.  The  laminae  of  the  bony  socket 
have  been  absorbed  and  transformed  into  "fibrous  intervening  tissue,"  infil- 
trated with  inflammatory  cells  and  products,  s.  Sequestrum  undergoing  pe- 
ripheral absorption;  i.  Inflammatory  infiltration  of  the  tissues. 

In  those  parts  of  the  bone  which  contain  cancellous  spaces  filled 
with  marrow — i.e.,  lower  down  the  sides  of  the  cementum  of  the 
teeth — the  changes  just  described  occur,  and  in  addition  a  lacunar 
absorption  follows. 

This  proceeds  from  the  side  of  the  periosteum  of  the  socket,  and 
also  from  the  Haversian  systems  by  means  of  osteoclasts  in  the  usual 
way.  The  foveolae  of  Howship  are  thus  produced.  Small  osseous 
sequestra  are  formed,  as  in  Fig.  279. 

Thus,  Znamensky  considers  that  it  is  not  produced  by  an  atrophy 
of  the  sockets  of  the  teeth.  Dr.  Nikiforoff,  quoted  by  this  author, ' 
says  in  his  "Pathological  Anatomy:"  "An  atrophical  state  of  the 
bones  shows  itself  by  a  thinning  or  disappearance  of  bone  tissue. 
In  some  cases  the  thinning  proceeds  as  a  result  of  the  Haversian 
canals  having  become  widened,  hence  termed  'osteoporous.'" 


''PYORRHCEA   ALVEOLARIS"  305 

There  are  two  kinds  of  atrophy  of  the  alveolus  originating  in  the 
bony  tissue  itself: — 

(i)  Simple  atrophy,  in  which  the  socket  disappears  completely; 
the  roots  become  denuded;  there  is  no  inflammation,  and  the  gum 
is  attached  but  lightly  to  the  periosteum  of  the  socket;  and 

(2)  Osteoporous  atrophy,  where  the  bone  is  thinned  at  the  expense 
of  the  Haversian  canals,  which  become  widened  ("osteoporous"); 
the  gum  comes  up  to  the  necks  of  the  teeth;  there  is  no  denudation 
of  the  root.  But  the  teeth  begin  to  loosen  on  account  of  the  osteo- 
porosis.    There  is  no  pus,  and  the  gum  is  normal. 

To  conclude.  If,  however,  chronic  inflammation  of  the  gum,  pro- 
duced by  the  presence  of  tartar  as  well  as  some  wasting  disease, 
occurs  when  osteoporous  atrophy  is  already  progressing,  then 
alveolar  "pyorrhoea"  inevitably  ensues.     (Znamensky.) 


CHAPTER  XII 

DEGENERATION  OF  THE  PERIODONTAL  MEMBRANE 

MICROSCOPICAL    ELEMENTS    IN: — (i)    The    fibrous    and    cellular   tissue; 
(ii)  The  areolar  spaces;  (iii)  Changes  in  the  neighbourhood. 

INTRODUCTORY 

It  would  seem,  prima  facie,  to  be  a  matter  of  surprise  that  the 
periodontal  membrane — that  thin,  structurally  insignificant  and 
uninteresting  delicate  periosteum  that  covers  the  roots  of  the  teeth 
of  man — should  ever  present  many  or  even  any  pathological  changes 
for  examination  by  the  dental  surgeon  or  pathologist,  or  open  up  to 
him  new  fields  for  investigation  and  research,  as  macroscopically 
it  appears  so  unimportant  and  so  far  beneath  his  serious  contempla- 
tion. But  second  consideration  reminds  one  that  it  is  a  fibrous 
tissue  analogous,  homologous,  and  practically  identical  both  anatom- 
ically,.  physiologically,  and  pathologically  with  the  periosteum  of 
bones.  And  when  this  fact  is  recalled,  and  thoroughly  recognised,  it 
is  not  difficult  to  understand  that,  as  a  consequence  of  disturbances 
in  or  loss  of  the  functional  activity  of  its  cellular  and  fibrous  elements, 
or  as  a  result  of  certain  metabolic  processes  occurring  therein,  it 
can  and  sometimes  does  undergo  metamorphoses  of  disintegration 
or  atrophy  on  the  one  hand,  or  abnormal  forms  of  growth  and  pro- 
liferation on  the  other;  and  that  incidental  to  these  retrogressive 
or  progressive  changes  it  may,  almost  as  much  as  the  periosteum  of 
the  jaws  and  long  bones  themselves,  inflame,  degenerate,  or  give 
origin  to  neoplasms  of  either  a  benign  or  a  malignant  nature. 

The  progressive  transformations  of  this  tissue  have  been  narrated 
in  Chapter  X. 

Degeneration  of  an  organ  in  general  pathology  usually  implies  a 
gradual  retrogressive  alteration  in  its  component  parts,  brought 
about  in  the  first  instance  in  one  or  more  various  ways.  If  cellular 
protoplasm  becomes  converted  by  an  abnormal  intracellular  meta- 
bolism indirectly  into  functionless  but  non-necrotic  and  non- 
irritating  tissue,  and  actual  death  does  not  supervene,  a  form  of  de- 
generation of  the  parts  is  established.     Thus  fatty,  colloid,  mucoid, 

306 


DEGENERATION   OF   THE   PERIODONTAL   MEMBRANE 


307 


calcareous,  or  other  degenerations  are  types  of  well-known  changes 
induced  by  conversion  of  the  cytoplasm  into  several  kinds  of  morbid 
and  useless  substances,  and  are  often  followed  by  cell-destruction; 
but  the  dental  pulp,  the  periodontal  membrane,  and  the  soft  parts 
found  in  the  Haversian  and  medullary  canals  of  neighbouring  bones, 
seem  sometimes  to  be  able  to  undergo  degenerative  atrophy  on 
which  neither  necrobiosis  nor  necrosis  can  possibly  follow. 


Fig.  280. — Transverse  section  of  fibroid  degeneration  of  the  pulp,  cut  in  situ. 
Prepared  by  "fixing"  and  hardening  in  alcohol  and  formaldehyde,  and  decalcified 
by  the  author's  method.  Stained  with  Ehrlich's  acid  hsmatoxylene.  d.  Dentine 
with  tubules;  f.o.  Fibroid  odontoblasts;  p.  Atrophied  pulp  tissue;  Cf.  with  follow- 
ing figures.      Magnified  170  diameters. 


--F  O 


The  disease  about  to  be  described  is  of  the  nature  of  a  fibrosis  or 
hyperplasia  of  the  individual  connective  tissue  fibres  and  cells  of 
these  soft  organs — the  precise  clinical,  histological,  or  pathological 
processes  which  have  produced  such  results  being,  at  present,  very 
obscure  and  hard  to  trace.  It  is  probably  due  to  an  exaggerated 
localised  lack  of  nutrition  induced  by  senile  changes  in  the  body 
generally — not  a  simple  atrophy  in  which  there  is  a  decrease  in  the 
'^ize  or  number  of  cells  or  fibres,  but  a  degenerative  or  marantic  or 


3o8 


THE    DENTAL    TISSUES 


senile  condition  where  the  protoplasm  and  the  nuclei  of  the  cells 
are  altered  completely. 

Descriptions  of  fibroid  degeneration  are  not  generally  found  in 
text-books  of  pathology,  and  this  probably  can  be  accounted  for  by 
the  fact  that  it  seems  to  be  limited  chiefly  to  those  vascular  struc- 
tures which  are  situated  within  or  between  hard  osseous,  unyielding 
walls. 

Regarding  this  from  a  dental  standpoint,  these  peculiar  anatomical 
relationships  obtain  only  in  the  mouth  and  jaws:  in  the  first  instance 


M  ,  . 


Fig.  281. — Transverse  section  of  fibroid  degeneration  of  the  alveolo-dental 
periosteum,  cut  in  situ.  Prepared  and  stained  as  in  preceding  figure,  d. 
Dentine;  c.  Cementum;A.  Alveolar  bone;  m.  Atrophied  root-membrane.  Mag- 
nified 50  diameters. 


the  pulp  inclosed  in  its  dentinal  environment,  in  the  second  the  root- 
membrane  limited  by  cementum  internally  and  by  alveolar  bone 
externally,  and  again  the  medullary  tissues  surrounded  so  securely 
by  the  concentric  lamellae  of  the  Haversian  systems  of  the  alveolar 
processes  of  the  maxillary  and  mandibular  bones.  In  this  manner 
the  omission  may  be  explained,  but  that  the  conditions  represented 
by  the  term  "fibroid  degeneration"  do  exist  there  is  no  possible 
doubt  whatever. 


DEGENERATION   OF   THE   PERIODONTAL   MEMBRANE 


309 


The  author  in  1892  drew  attention  to  a  frequent  degeneration  of 
the  dental  pulp  which  on  comparison  with  the  similar  condition  of 
the  periodontal  membrane  bears  a  curious,  interesting,  and  instructive 
resemblance  to  the  latter.  A  casual  glance  at  Figs.  280  and  283  shows 
that  fibroid  degeneration  of  both  are  almost  homeomorphous.  A 
reference  to  the  etiology  and  patho-histology  of  the  former  will 
throw  some  hght  on  the  chnical  and  pathological  histories  of  the 
latter. 


Fig.  282. — Transverse  section  of  the  same.  Prepared  as  in  Fig.  126.  Stained 
with  haematoxylene  and  counterstained  with  warm  ammonia-picro-carmine. 
c.  Cementum;  m.  Root-membrane;  a.  Alveolar  bone;  H.  Enlarged  (osteoporous) 
medullary  spaces.      Magnified  120  diameters. 

Briefly,  it  may  be  mentioned  that  fibrosis  of  the  pulp  is  simply  a 
"natural  old-age  termination  of  the  hfe  of  a  healthy  pulp"  which 
has  survived  any  attacks  of  an  endogenetic  or  exogenetic  character. 
It  is  not  dependent,  in  the  least  degree,  on  inflammation  of  that 
organ,  but  attendant  on  senile,  marantic,^  constitutional  changes. 
Several  writers  in  America  and  on  the  continent  of  Europe  have 
described  certain  affections  which  may  be  allied  to  or  even  be  pre- 

iHektoen  and  Riesman.     A  Text-book  of  Pathology,  vol.  i.,  1901. 


3IO 


THE    DENTAL    TISSUES 


Fig.  284. 
Figs.   283  and  284. — Transverse  sections  of  the    same.      Prepared  similarly. 
Stained  with  iron  perchloride  and  tannic  acid.      c.   Cementum;  a.  Alveolar  bone; 
M.  Root-membrane.     Magnified  266  diameters. 


DEGEXEEATION    OF   THE   PERIODONTAL   MEMBRANE  311 

cursors  of  this  fibrosis,  notably  the  areolation  and  oedema  described 
by  Black,  the  reticular  atrophy  of  Wedl,^  and  the  ''Atrophia  pulpce 
scleroticans^'  of  Rothmann.- 

But  in  complete  fibroid  degenerations  there  are  no  cells  of  any 
description,  no  nuclei,  no  odontoblasts,  no  nerve  fascicuh,  and  no 
blood-vessels;  while  the  connective  tissue,  "which  is  but  a  loose  mass 
of  network  in  the  normal  state,  has  become  grossly  hypertrophied 
or  quite  obHterated,  and  its  place  taken  by  a  new,  firm,  fibrous 


M  A  A 

Fig.  285. — Transverse  section  of  the  same.  Prepared  as  before.  Stained 
with  hEematoxylin.  c.  Cementum;  M.  Root-membrane;  a.  Alveolar  '  bone ; 
A. A.  Structureless  alveolus  mentioned  in  the  text.      Magnified  160  diameters. 

structure  devoid  of  cells,  nuclei,  or  any  regular  arrangement  of 
constituent  parts:"  see  Chapter  VII,  Vol.  II. 

There  is  therefore  a  remarkable  coincidence  in  the  microscopical 
characteristics  of  complete  fibrification  of  the  pulp  and  the  root- 
membrane;  but  there  are  two  important  differences.  One  is  that, 
in  the  pu]p,  the  whole  of  the  organ  becomes  simultaneously  and 

^  Atlas  zur  Pathologic  der  Zahne,  1869. 
2  Pathologic  der  Zahnpulpa  und  Wurzelhaut,  1889. 


312  THE   DENTAL   TISSUES 

perhaps  suddenly  metamorphosed,  while  in  the  alveolo-dental 
periosteum,  and  in  a  lesser  degree  in  the  spaces  of  the  osteoporous 
alveolar  bone,  the  changes  which  lead  up  to  a  perfect  fibrosis  can  be 
observed  taking  place  side  by  side  within  the  same  area;  the  other, 
that  whereas  fibrosis  of  the  pulp  affects  only  that  tissue,  that  of  the 
periodontal  membrane  affects  not  the  cementum,  but  the  bone  of 
the  socket,  which  in  its  turn  shares  the  innutrition  of  the  vascular 
periosteum.  It  may  be  remarked,  however,  that  fibrosis  of  the 
pulp  and  the  root-membrane  and  the  soft  tissue  in  the  osteoporous 
bone  may  occur  synchronously  as  a  result  of  the  general  senile 
changes  in  the  hard  parts  of  the  buccal  cavity. 

An  examination  of  the  mouths  of  elderly  people  often  reveals, 
associated  with  absorption  of  the  alveolar  processes  of  the  jaws, 
the  presence  of  sound  but  aged  and  yellow  teeth,  portions  of  whose 
roots  are  exposed.  The  cementum  is  laid  bare,  and  the  periosteum 
gone.  The  teeth  may  be  very  loose  or  fairly  firm,  free  from  pain 
or  afflicted  with  a  subacute  periostitis  as  the  result  of  sudden  trau- 
matism. Chemical  or  thermal  stimuli  yield  no  effect.  If  the 
alveolo-dental  membrane  of  such  teeth  as  these  has  never  been 
subjected  to  disease,  but  has  simply  run  its  life-course  and  has  now 
become  atrophied,  fibrosis  has  most  likely  occurred;  and  the 
microscopical  study  of  such  a  membrane  is  rewarded  by  the 
discovery  of  certain  new  histological  appearances  which  can  now  be 
described  in  fuller  detail. 

HISTOLOGY 
(i)   The  Fibrous  and  Cellular  Tissues 

In  places  the  fibres  are  thin  and  delicate  at  the  edge  of  the  cemen- 
tum (Fig.  281),  but  as  they  unite  to  pass  obliquely  outward  they  in- 
crease in  diameter  and  coarseness,  here  (Fig.  282)  being  thickly 
meshed  together  in  broad  long  bundles  or  sheaves  with  but 
little  branching;  there,  more  sparse  and  sending  out  inosculating 
branches  (Fig.  283).  Their  attachment  is  very  strong  both  exter- 
nally, and  their  free  extremities  seem  to  be  "built  into"  the  hard 
tissues  (Fig.  284).  The  thinner  fibres  are  structureless,  possess 
clear  double  contours,  and  branch  freely.  A  nucleus  of  a  connec- 
tive tissue  cell  may,  at  times,  be  retained,  but  the  reticular  appear- 
ance of  the  thinnest  fibres  resembles,  at  a  glance,  the  stellate  re- 
ticulum of  the  enamel  organ  minus  its  cells,  at  the  period  when  it 
is  about  to  disappear. 

As  the  thin  fibres  increase  in  size,  it  is  seen  that  they  are  composed 


DEGENERATION   OE   THE   PERIODONTAL  MEMBRANE  313 

of  fine  Strands  running  parallel  with  one  another,  until  in  places 
they  may  extend  across  the  intervening  space  as  thick  shapeless 
masses  separated  from  one  another  by  areolae  of  varying  size  and 
form.  (Fig.  285).  They  pass  in  a  wavy  direction  similar  to  the  un- 
dulating character  of  white  connective  tissue  fibres,  and  like  them 
have  fusiform,  triangular  or  ovoid  cells  generally  arranged  in  rows 
running  parallel  with  the  fibres  themselves— that  is,  obhquely 
outward.     Their  nuclei  are  apparently  atrophied,  and  do  not  ex- 


c  — 


r-^mc^^mmsiF  ^^ ': 


^i 


.\-  -.  h'S 


'i.l\ 


s 


Fig.  286. — Transverse  section  of  the  same.  Preparation  and  staining  similar. 
c.  Cementum;  a.  Alveolar  bone;  f.  Fibres  with  degenerated  cells  and  nuclei. 
Magnified  300  diameters. 

hibit  the  nucleoli  or  the  karyoplasm  or  chromatin  found  in  the  same 
cells  in  a  young  periodontal  membrane — facts  well  demonstrated 
when  the  sections  are  stained  with  Ehrlich's  acid  haematoxylene 
followed  by  warm  ammonia-picro-carmine  as  in  Fig.  282. 

These  prominent  aggregations  of  connective  tissue  bundles  are 
probably  merely  the  atrophied  remains  of  the  "principal  fibres" 
of  Black. 


314 


THE    DENTAL    TISSUES 


All  traces  of  osteoblasts  have  vanished  absolutely,  a  few 
decrepit  nuclei  alone  indicating  their  anatomical  positions  in  the 
membrane;  and  there  are  no  epithelial  "rests"  of  Malassez. 
There  may  be  a  little  granular  detritus  here  and  there,  as  also  the  ap- 
pearance of  fatty  degeneration.  But  this  latter  most  likely  marks 
the  commencement  of  the  areolation  already  mentioned. 

(ii)   The  Areolar  Spaces 

Interesting  as  are  these  changes,  the  most  striking  point  about  sec- 
tions of  fibroid  degeneration  are  the  areolae  newly  developed  in  the 


Fig.  287. — Longitudinal  section  (apical  region)  of  fibroid  degeneration  of  the 
alveolo-dental  periosteum.  Preparation,  staining,  and  magnification  as  in  Fig. 
285.  D.  Dentine;  c.  Cementum;  a.  Alveolar  bone;  M.  Root-membrane;  G.  Gum 
tissue. 


tissue.     In  many  instances  they  extend  right  across  the  thickness — 
or   rather  the  thinness — of  the  periodontal  membrane  (see  Figs. 
281  and  287).     The  larger  ones  measure  310/i  and  more,  the  smaller 
2/x  to  2o^i,  the  average  being  perhaps  6oju. 
They   are   found   in   great  numbers,  they  vary  in  shape,  being 


DEGENERATION   OF   THE   PERIODONTAL  MEMBRANE 


315 


tubular,  oval,  or  round,  and  they  are  bounded  and  supported  by 
strong  curved  fibres  which  pass  almost  circularly  around  them.  They 
are  in  no  sense  the  remains  of  the  blood-vessels,  as  they  are  not  con- 
fined to  the  central  zone  of  the  membrane,  which  is,  more  or  less, 
the  rule  in  normal  conditions.  In  addition  they  do  not  possess  the 
definite  walls  of  arteries,  veins,  and  capillaries.  They  are  perhaps 
more  marked  and  obtrusive  in  transverse  than  in  longitudinal  sec- 
tions (Fig.  286).  Distributed  fairly  evenly  throughout  the  mem- 
brane, they  extend  into  the  recesses  of  the  osteoporous  alveolus. 


Fig.  288. — Transverse  section  of  the  root  membrane  of  an  aged  tooth.  Prepa- 
ration, staining,  and  magnification  as  in  Fig.  281,  d.  Dentine;  c.  Cementum; 
M.   Root  membrane;  a.   Alveolar  bone.      Cf.  cementum  in  Fig.  281. 


The  width  between  the  bone  and  cementum  is  but  little  di- 
minished, and  differs  thus  from  mere  senile  changes  (Figs.  288  and 
289).  It  measures  in  its  thinnest  portion  about  150^1.  But  it  is  a 
noticeable  feature  of  these  sections  that  the  bays  or  recesses  of  the 
alveolar  bone  are  more  exaggerated — doubtless  not  through  absorp- 
tion, as  in  the  case  of  old  teeth  affected  by  ''pyorrhoea  alveolaris" 
(see  Figs.  290  and  291  j,  but  on  account  of  the  general  osteoporosis 
which  has  occurred. 


3i6 


THE    DENTAL    TISSUES 


(iii)  Changes  in  the  Neighbourhood 

It  is  a  noteworthy  fact  that  the  cementum,  although  sHghtly 
thicker  than  normal,  is  not  hyperplasic,  the  majority  of  the  sections 
cut  by  the  author  being  free  from  lacunas  and  canaliculi  (Figs.  281, 
284,  286,  and  292). 

The  osteoporosis  of  the  alveolus  is  very  pronounced,  and  the  en- 
larged Haversian  canals  are  filled  with  a  shrunken  fibroid  tissue  of  a 


:4%^i#Afi«i.5A.. 


,.^  B 


Fig.  289. — Transverse  section  of  periodontal  membrane  of  the  tooth  with 
acute  "pyorrhoea  alveolaris,"  from  the  mouth  of  a  man  aged  seventy-one  years. 
Prepared  and  stained  as  above,  c.  Cementum;  a.  Alveolar  bone;  m.  Root-mem- 
brane; B.  Blood-vessels;  O.   Osteoblasts.      Magnified  260  diameters. 

character  resembling  that  which  is  found  between  the  "principal 
fibres"  of  the  root  membrane.  Most  of  these  spaces  in  the  bone, 
which  are  usually  rounded,  exhibit  one  or  more  large  coarse  areolae, 
possibly  and  probably  the  remains  of  thQ  vascular  system  (Fig. 
293).  There  are  no  red  marrow  cells,  no  myeloplaxes,  no  connective 
tissue  cells,  no  blood  corpuscles — nothing  but  an  innutritious  non- 
typical  reticulum  of  coarse  and  fine  fibrous  bundles. 


DEGENERATION   OF   THE   PERIODONTAL   MEMBRANE         317 


oc 


"**■■  -^       fc*2^ 


Fig.   290. — Same    as    preceding,      c.    Structureless  cementum;   d.   Dentine;   oc. 
Osteoclasts.      Magnified  220  diameters. 


A 


.-M 


!■(',.  2^1 .  S;iin'-,  iHT'i);ir<.-(l  hy  Weil's  balsam  niethod.  u.  Dentine;  C. 
Structureless  cementum;  m.  Root-membrane;  A.  Osteoporous  alveolus;  F.  How- 
ship's  foveola2,  produced  by  absorption  by  means  of  the  osteoclasts.  Magnified 
120  diameters. 


THE    DENTAL    TISSUES 


Fig.  292. — Transverse  section  of  fibroid,  degeneration  of  the  alveolo-dental 
periosteum.  Stained  with  iron  perchloride  and  tannic  acid.  Shows  the  general 
appearance  of  the  tissue.      Magnified  50  times. 


Fig.  293. — Osteoporous  alveolar  bone.  Stained  with  lia;niaUj.\yline.  C. 
Concentric  lamella;  i.  Intermediary  lamellag;  H.  Enlarged  Haversian  canal  or 
cancellous  space;  f.  Fibroid  degeneration  of  the  medullary  tissue;  b.  Atrophy  of 
artery  (?)      Magnified  250  diameters. 


DEGENERATION   OF   THE   PERIODONTAL  MEMBRANE  319 

The  lacunas  of  the  Haversian  systems  are  generally  speaking 
abrachiate;  and  that  part  of  the  bone  itself  which  is  immediately 
contiguous  to  the  periodontal  membrane  has  undergone  micro- 
scopical alteration  and  degeneration  in  which  the  structure  of  the 
concentric  and  intermediary  lamellae  are  not  only  masked,  but  in 
some  instances  entirely  lost  and  unrecognisable  (see  Fig.  285). 

There  is  no  calcification  of  any  of  the  parts  of  the  root  membrane, 
no  progressive  ossification  or  osteoplastic  signs,  no  attempts  at 
ankylosis;  everything  points  to  retrogressive  changes  pure  and 
simple. 

It  would  be  indeed  surprising  if,  all  the  other  soft  tissues  degen- 
erating as  has  been  seen,  the  gum  in  the  immediate  vicinity  should 
escape.  It  does  not,  but  partakes,  in  its  turn,  of  the  general  effects 
of  the  loss  of  nutrition  (Fig.  287).  It  is  only  necessary  to  add  that 
it  becomes  much  attenuated  both  in  its  epithelial  and  sub-epithe- 
lial portions,  more  coarsely  fibrous  and  less  vascularised  than  usual, 
and  may,  wholly  or  in  part,  undergo  fatty,  fibroid,  or  other  old-age 
changes. 


PART  II 
THE  ORAL  TISSUES 


CHAPTER  XIII 

THE  PATHOLOGICAL  CONDITIONS  OF  THE  GUMS, 
PALATE,  ANTRUM,  AND  JAWS 

Microscopical  Elements  in: — (i)  Inflammation  of  the  gum;  (ii)  Hyper- 
trophy of  the  gum;  (iii)  Fibroma;  (iv)  Spindle-celled  sarcoma;  (v) 
Round-ceUed  sarcoma;  (vi)  Giant-celled  sarcoma;  (vii)  Melanotic 
sarcoma;  (viii)  Endothelioma;  (ix)  Papilloma;  (x)  Hsem-angioma; 
(xi)  Osteoma;  (xii)  Adenoma;  (xiii)  Carcinoma;  (xiv)  Syphilis;  (xv) 
Inflammation  and  carcinoma  of  lining  membrane  of  the  antrum  of 
Highmore;  (xvi)  Tumours  of  the  jaws. 

The  following  diseases  of  the  soft  parts  of  the  buccal  cavity  and  its 
accessory  sinus  are  among  the  more  common  affections  which  come 
under  the  immediate  notice  of  dental  surgeons.  It  is  not  easy  to 
arrange  them  in  anatomical  order,  and  their  classification  in  an  alpha- 
betical list  is  inconvenient.  They  are  here  briefly  described  from 
the  clinical  and  pathological  standpoints,  which,  it  is  hoped,  will  be 
of  service  to  the  reader. 


OF    THE    GUMS   AND   PALATE 

(i)  Inflammation  of  the  Gum 

Inflammation  of  the  gum  {gingivitis)  may  be  acute  or  chronic, 
diffuse  or  local  (marginal). 

Causes. — Chronic  irritation  from  the  presence  of  foreign  bodies 
such  as  tartar,  edges  of  fillings,  ill-fitting  metallic  crowns  or  clasps. 
"The  blue  line"  of  chronic  lead  poisoning  is  a  chronic  general 
gingivitis. 

HISTOLOGY 

The  soft  tissues  are  infiltrated  with  inflammatory  cells  and  pro- 
ducts. The  oral  epithehum  may  be  unaffected  and  the  terminal 
free  edge  of  the  alveolar  process,  at  first  is  unabsorbed.  The  vessels 
are  hyperaemic. 

322 


DISEASES    OE    THE    GUMS    AND    JAWS 


323 


Fig.  294. — Acute  gingivitis  round  a  loose  second  incisor  in  mouth  of  a  woman 
aged  fifty.  Stained  with  haematoxylene  and  eosine.  d.  Dentine;  c.  Cementum; 
B.  Edgeof  alveolar  bone;  e.  Oral  epithelium;  g.  Inflamedgum;  p.  Periodontal 
membrane.      Magnified  45  times. 


324 


THE    ORAL    TISSUES 


(ii)    Hypertrophy  of  the  Gum 

GENERAL    CHARACTERISTICS 

Definition. — A    non-inflammatory  localised  increase  of  the  sub- 
stance of  the  gum,  chiefly  apparent  round  the  necks  of  the  teeth, 


Fig.   295. — The    same  as  the  preceding  figure.      Magnified  200  times.     o.E. 
Oral  epithelium;  c.   Cellular  infiltration  of  the  sub-mucous  tissue. 

due  to  augmentation  of  the  size  or  of  the  number  of  its  cells,  or  of 
both,  without  any  appreciable  alteration  in  its  structure.  Syno- 
nym: "Polypus"  of  the  gum — an  illiterate  term. 


DISEASES    OF    THE    GUMS    AND    JAWS 


325 


Its  etiologv  is  but  imperfectly  understood.  Some  forms,  occurring 
in  the  mouths  of  young  children,  suggest  congenital  origins;  but 
acquired  forms  are  certainly  due  to  functional  increase  and  nutri- 


A  B 

Fig.  296. — A  mandibular  molar  presenting  a  true  hypertrophy  of  the  gum 
associated  with  the  periodontal  membrane  at  its  cervical  margin,  a.  Shows  the 
new,  pedunculated  growth,  dislodged  from  the  carious  cavity  into  which  it  had 
extended — thus  simulating  a  chronic  hyperplasic  inflammation  of  the  pulp,  and 
its  periosteal  attachment.  B.  Shows  the  position  it  occupied  normally  in  regard 
to  the  tooth  itself. 

tive  supply  from  any  cause  whatsoever.     Localised  hypertrophies 
are  often  induced  by  local  irritation,  as  from  tartar,  "pyorrhoea 


Fig.  297. — Hypertrophy  of  the  gum.  Prepared  by  "fixing"  and  hardening 
in  formalin  and  alcohol.  Stained  with  Ehrlich's  acid  hsematoxylene.  Mag- 
nified 45  times.     o.E.   Oral  epithelium;  s.  Submucous  tissue. 

alveolaris,"  etc.     Such  cases  are  not  true  examples  of  the  condition, 
but  may  be  termed  "inflammatory  hypertrophies." 


326 


THE    ORAL    TISSUES 


HISTOLOGY 

The  mucous  membrane  is  generally  unaffected,  and  the  sub- 
mucous tissue  may  project  into  it  in  the  form  of  papillae,  or  these  may 
be  absent. 

The  bulk  of  the  tumour  is  composed  of  connective  tissue  fibres, 
which,  somewhat  coarser  than  usual,  interlace  in  every  direction. 
While,  in  some  instances,  the  vascular  system  is  largely  increased  in 
the  sub-epithehal  regions,  the  cellular  elements,  scanty  in  the  nor- 
mal gum,  are  much  multiplied.  Here  are  found  many  connective 
tissue  cells,  crowds  of  leucocytes  (polymorphonuclear  neutrophiles, 


Fig.  298. 


-Similar  to  the  preceding.      Preparation,  staining  and   magnification 
the  same.      c.    Coarse  connective-tissue  fibres. 


eosinophiles  and  lymphocytes),  some  mast  cells  {Mastzellen),  mainy  of 
the  plasma-cells  of  Unna,  and  many  lymphoid  cells.  The  leuco- 
cytes are  seen  in  the  tissue  spaces,  around  the  blood-vessels,  and 
lie  between  the  coarse  fibres  of  connective  tissue.  Unna's  cells  may 
be  scattered  throughout  the  substance  of  the  growth,  and  the  mast 
cells  (whose  granules  are  capable  of  becoming  specifically  stained  by 
means  of  the  basic  aniline  dyes,  e.g.,  gentian  aniline  violet),  can  be 
noticed  at  the  advancing  margins  of  the  new  growth. 

In  addition,  sections  will  sometimes  show  clusters  of  cells  which, 
at  first  sight,  resemble  the  epithelial  cell-nests  which  are  patho- 


DISEASES    OF    THE    GUMS    AND    JAWS 


327 


gnomonic,  when  found  in  certain  situations  in  carcinomata,  mixed  up 
with  lymphoid  cells  and  a  certain  amount  of  fat  cells. 

Roe,  of  Philadelphia,  examined  sections  of  hypertrophy  of  the 
gum  from  a  bacteriological  standpoint,  and  found,i  on  using  Weig- 
ert's  staining  method,  many  saccharomyces  present  in  the  tissues. 

He   concludes    (p.  350):— "The   pathology indicates 

that  this  disease  is  not  a  true  hypertrophy,  but  should  be  classed 
with  the  infectious  granulomata;  and,  in  keeping  with  the  estabHshed 
nomenclature,  I  would  propose  calUng  it  Saccharomycosis,  caused  by 
saccharomycetes. ' ' 


TUMOURS    OP    THE    GUMS    AND    JAWS 

Definition. — A  tumour  is  a  new  growth,  not  produced  by  inflam- 
mation or  mere  hypertrophy  of  pre-existing  tissue,  which  shows  no 
tendency  to  undergo  spontaneous  cure  or  yield  to  the  action  of  drugs. 

A  homologous  tumour  resembles  and  grows  in  the  tissue  in  which  it 
originates;  e.g.,  fibroma  of  the  periodontal  membrane. 

A  heterologous  tumour  originates  in  one  type  of  tissue  and  retain- 
ing the  features  of  that  type,  invades  and  replaces  another  type;  e.g., 
carcinoma  of  the  gums,  palate,  etc. 

Clinically,  it  is  either  (i)  innocent  or  malignant,  and  (2)  cysticor  soHd. 

Innocent  or  benign  tumours,  differ  from  malignant  tumours  in  the 
following  particulars: 

Differential  Diagnosis  of 


Innocent  tumours 


Malignant  tumours 


I.  Grow  slowly. 

I.  Grow  rapidly. 

2.  Resemble  fully-formed  tissues. 

2.  Do  not. 

3.  Encapsuled. 

3.  Non-encapsuled;  infiltrate  neighbour- 
ing structures. 

4.  Movable. 

4.  Fixed. 

5.  Lymphatic  system  not  involved. 

5.  Involved. 

6.  No  dissemination  in  distant  organs. 

6.  Spread  by  embolism. 

7.  No  constitutional  symptoms. 

7.  Cancerous  cachexia. 

8.  No  recurrence  after  removal. 

8.  Often  recur. 

1  The  Denial  Cosmos,  [).  347,  igot. 


328 


THE    ORAL    TISSUES 


Histologically,  tumours  are  classified  as 
I.  Connective  tissue  tumours. 

A.  Fully-formed   connective   tissue   type,   e.g.,  fibrous,  fatty, 
cartilaginous,  osseous,  etc. 

B.  Complex  connective  tissue  type,  e.g.,  blood-vessels,  lymph 
vessels,  etc. 

C.  Young  or  embryonic  tissue  type,  e.g.,  round  cells,  spindle- 
cells  or  giant  cells. 

II.  Epithelial  and  Glandular  tumours.     Squamous,  spheroidal,  or 
cylindrical  (columnar)  type. 
111.  Teratoma.     A  rare  tumour,  generally  of  the  ovaries,  containing 
teeth,  hair,  pultaceous  secretions,  etc.     See  Chapter  XVII. 
They  are  thus  named: 
I.  A.  Fibroma,  lipoma,  enchondroma,  osteoma,  papilloma,  etc. 

B.  Angioma    or    haemangioma    or    naevus,     lymph-angioma, 
lymphadenoma,  endothelioma,  etc. 

C.  Round-celled  sarcoma,  spindle-celled  sarcoma,  mixed-celled 
sarcoma,  giant-celled  or  myeloid  sarcoma. 

II.  Squamous-celled  carcinoma  or  epithelioma.     Cylindrical-celled 
carcinoma. 
Adenoma. 

Differential  Diagnosis  of 


Sarcoma 

Carcinoma 

I.  Youth  and  early  age. 

I.  Old  age. 

2.  Each  cell  is  completely  surrounded  by  varying 
amount  of  intercellular  material,  which  does 
not  form  alveolar  spaces;  blood-vessels  ramify 
amongst  the  cells. 


2.  Cells  in  alveolar  spaces; 
blood-vessels  ramify  in  con- 
nective tissue  stroma. 


3.  Disseminates  by  blood-vessels*  (veins). 

3.  Disseminates  by  lymphatic 
system. 

4.  Haemorrhages  frequent. 

4.  Haemorrhages  infrequent. 

INFLAMMATORY    AND    NON-INFLAMMATORY   SWELLINGS   OF  THE   JAWS 

These  may  be  classified  as  arising  in 
A.  The  Maxillce: 

1.  Those  involving  the  maxillary  sinus. 

2.  Those  involving  the  alveolar  process. 

3.  Those  involving  the  palate. 

*  Except  in  the  case  of  the  tonsil,  testis,  and  thyroid  body. 


DISEASES    OF    THE    GUMS    AND    JAWS 


329 


B.  The  Mandible: 

1.  Those  arising  from  the  mucous  membrane  arid  periosteum. 

2.  Those  arising  between  the  external  and  internal  alveolar 
plates. 

A 

SWELLINGS    OP    THE    MAXILL.E 

I.  SwelHngs  of  the  antrum  are 

1.  Those  arising  locally:  ' 

(a)  Fluid — mucous  cyst. 

(b)  Solid- — adenoma,  sarcoma,  carcmoma. 

2.  Those  arising  by  invasion:  fibroma,  enchondroma,  osteoma, 
round,  spindle-celled  and  melanotic  sarcoma,  carcinoma. 


Differential  Diagnosis  01 

Fluid  Swellings  of 

A-Lveolar  Processes 

Acute 
abscess 

Chronic 
abscess 

Dental  cyst 

Follicular 
odontoma 
(simple) 

Epithelial 
odontome 

I-  Age 

Any. 

Any. 

Adult. 

Child. 

Young  adult. 

2.  Pain 

Great. 

Not  great. 

Slight  on 
pressure. 

None. 

None. 

3.  Rate  of  growth. 

Rapid. 

Rapid  at 
first;  varies. 

Slow; 
progressive 

Slow; 
progressive 

Very  slow. 

4.  Appearance     of 
mucous  membrane 

Acutely 
inflamed. 

Inflamed. 

Normal. 

Normal. 

Normal. 

5.    Definition 

Large  area. 

Small  area. 

Small  area; 
globular 
outline. 

Large  area; 

well 

defined. 

Large    area ; 
not  well 
defined. 

6.  Walls 

Thin. 

Thick. 

Very  thin. 

Very  thin. 

Thin. 

7.  Fluctuation. .  .  . 

Non-elastic 

None. 

Elastic. 

Elastic. 

None. 

8.  Tooth 

Carious 
and  septic. 

Carious 
and  septic. 

"Dead." 

Absent. 

Absent. 

9.  Radiograph. .  .  . 

Outline 
clearly 
defined. 

Outline 
not  so 
clearly 
defined. 

Very  clear 
outline. 

Good 

definition; 

tooth  in 

cavity. 

Not  very 
good  defini- 
tion;    tooth 

generally 
absent. 

33° 


THE    ORAL    TISSUES 


II.  Swellings  of  the  alveolar  processes  are 

1.  Those  arising  from  surface — fibroma  (so-called  "epulis"). 

2.  Those  arising  from  interior: 

(a)  Fluid — acute  abscess,  chronic  abscess,  dental  cyst,  follicular 
odontome,  epithelial  odontome. 

(b)  Solid — fibroma,  calcified  odontome,  sarcoma,  carcinoma. 
III.  Swellings  of  the  palate  are 

(o)  Fluid — acute  or  chronic  abscess  from  second  maxillary 
incisor,  dermoid  cyst  of  soft  palate.  Rarely,  simple  folli- 
cular odontome,  and  aneurysm  of  descending  palatine 
artery. 

(b)  Solid — innocent  tumours,  viz.,  fibroma,  papilloma, 
adenoma,  osteoma.  Malignant  tumours,  viz.,  sarcoma 
and  carcinoma. 


Differential  Diagnosis  of  Solid  Swellings  of  the  Palate 


Rate  of  growth 

Characteristics 

Frequency  of 
occurrence 

Situation 

Fibroma 

Slow. 

Pedunculated. 

Common. 

Osteoma 

(Torus  palalinus) 

Exceedingly 

slow. 

Flat. 

Common.    Hard  palate. 

Adenoma 

Slow. 

Sessile. 

Rare. 

Sarcoma 

Very  rapid. 

:  Hard  palate. 

Carcinoma 

Very  rapid. 

Soft  palate. 

SWELLINGS    OF    THE    MANDIBLE 

1.  Of    mucous    membrane   or  periosteum:  fibroma,   enchondroma, 
osteoma,  sarcoma  and  carcinoma. 

2.  Of  interior: 

(c)  Fluid — acute  and  chronic  abscess,  dental  cyst,  follicular  odon- 
tome, epithelial  odontome. 
{b)  Solid — sarcoma  (usually  myeloid) ,  squamous-celled  carcinoma. 


DISEASES    OF    THE    GUMS    AND    JAWS  33 1 

Differential  Diagnosis  of  Swellings  of  Exterior 


Situation 

Skin  or  mucous   membrane 

Fibroma 

....    Median  line. 

Not  involved. 

Enchondroma 

....    Inner    side     in    premolar 
region. 

Not  involved. 

Osteoma 

....  Inner  side  in  premolar  re- 
gion, or  at  angle. 

Not  involved. 

Sarcoma. 


Ulcerates  primarily  or  sec- 
onda^ilJ^ 


Carcinoma Ulcerates  primarily. 

For  further  signs  and  symptoms,  see  above. 

Differential  Diagnosis  of  Swellings  of  Interior 


Rate  of  growth  1  Extent 


Appearance 


Fluid 


Slow.        !     Involves  outer  plate. 


_,  ,. ,  T,      •  1        It       ,        ,      ,      1  May  simulate 

bolid Rapid.  involves  both  plates.  .       .  , 

necrosis  of  bone. 


The  saHent  histological  characteristics  of  the  above  tumours  must 
now  be  described. 

I.    TUMOURS    OF    THE    FULLY-FORMED   CONNECTIVE    TISSUE    TYPE 

(iii)  Fibroma 

GENERAL   CHARACTERISTICS 

Definition. — A  connective  tissue  tumour  of  the  homologous 
type,  arising  from  the  osseous  tissues  (or  their  periosteum)  of  or 
underneath  other  parts  of  the  buccal  cavity.  Synonym:  "Fibrous 
epulis." 

The  term  "epulis"  [tin  upon,  ov\a  the  gums)  is  often  carelessly 
applied  to  a  true  fibromatous  type  of  neoplasm  which  is  of  constant 
occurrence.  "Epulis"  simply  means  "upon  the  gum,'''  and  if 
used  at  all  should  have  before  it  a  qualifying  adjective,  such  as 
"fibrous,"  "sarcomatous,"  &c.  Employed  per  se,  it  should  be 
deleted  from  all  dental  vocabularies. 


332 


THE    ORAL    TISSUES 


Etiology. — Congenital  influences  probably  have  some  share  in  the 
formation  of  these  growths;  and  it  is  just  possible  that  traumatism 
may  occasionally  give  rise  to  them. 

With  regard  to  the  first  hypothesis,  it  has  been  suggested^  that  as 
far  as  the  mandible  is  concerned  they  may  have  their  origin  in  some 
embryonic  "rest,"  left  at  the  time  of  fusion  of  the  two  halves  of 
Meckel's  cartilage;  and  as  far  as  the  palate  is  concerned,  they  may 
take  their  rise  from  the  sutures  existing  in  the  foetus,  between  the 
premaxillary  and  maxillary  bones.  This  theory  thus  corroborates 
J.  G.  Turner's  researches  on  the  subject. 


Fig.   299. — Fibroma    of   the    jaws,    rising   from   the   interdental    osseous    septa. 
Prepared,  stained  and  magnified  as  in  Fig.  297.      The  "hard"  variety. 


Situation. — Fibromata  are  usually  found  between  neighbouring 
teeth,  which  may  become  separated,  or  springing  from  the  labial 
or  buccal  surfaces  of  the  gum  covering  the  alveolar  processes  of  the 
jaws.  Arising  from  and  rarely  attached  to  the  periodontal  mem- 
brane, they  may  be  removed  during  the  extraction  of  teeth  (see  Figs. 
239,  240  and  241).  They  are  often  associated  with  the  periosteum 
of  the  interdental  septa  or  that  of  the  jaws. 

1  J.  H.  Targett,  "The  Pathology  of  certain  growths  about  the  Lower  Jaw." 
Trans.  Odonto.  Soc.  of  Great  Britain,  May,  1902. 


DISEASES    OF    THE    GUMS    AND    JAWS 


333 


Pathology. — In  the  mouth,  as  elsewhere,  two  kinds  may  be  found — 
the  soft  and  the  hard.  They  differ  in  that  the  former  is  much  more 
vascular,  and  has  its  constituent  parts  more  loosely  arranged  than  the 
latter.     They  agree  in  the  following  particulars: — 

In  shape  they  are  circumscribed  masses  roughly  spherical  or  oval 
in  outhne.  They  may  be  sessile  or  pedunculated,  nodular,  or 
flattened. 

Varieties. — Classified  pathologically,  they  are  called  "periosteal" 
and  "endosteal."     Of  firm  consistency,  on  sectionising  they  show, 


Fig.   300. — The  same.      Magnified  250  times. 

when  examined  in  the  gross,  a  white  glistening  surface,  with  strong, 
pale  bands  of  connective  tissue  fibres. 

In  the  mouth  they  are  usually  single. 

Secondary  Changes. — Superficial  ulceration,  and  calcification, 
wholly  or  in  part.  Rarely  hydropic  degeneration  of  the  epithelium 
may  occur,  and  lead  ultimately  to  mahgnancy.     See  Chapter  XIV. 


HISTOLOGY 


Sections  of  hard  fibromata  exhibit  dense  bundles  of  connective 
tissue  fibres  (mature  normal  fibrous  tissues),  which  interlace  in  all 


334 


THE    ORAL    TISSUES 


directions,  but  in  the  sub-epithelial  region  are  arranged  concentric- 
ally. The  blood-vessels  are  few  in  number,  and  lymph-spaces  are 
scanty.  The  cells  have  laterally  flattened  nuclei,  and  are  practically 
spindle-shaped  in  outline. 

The  soft  varieties  have  a  somewhat  embryonic  aspect,  as  that  of 
newly  forming  connective  tissue.  The  vessels  are  large  and  nu- 
merous. The  cellular  elements,  with  large  round  or  oval  nuclei, 
abound  in  great  quantities. 


Fig.   301. — The  same,  showing  some  of  the  characteristics  of  the  "soft"  variety. 

Magnified  45  times. 

Normal  mucous  membrane  is  present  on  the  surface  of  both 
varieties,  but  the  sub-epithelial  papillae  show  signs  here  and  there 
of  variations  from  the  normal  type.     "Spiny"  cells  are  constant. 


(iv)  Spindle-celled  Sarcoma 

This  is  one  of  the  commonest  forms  of  sarcoma,  and  may  be  hard 
or  soft.  The  spindle-celled  tumours  of  the  gums  may  be  quite  be- 
nign, or  may  pursue  a  malignant  course,  and  have  a  remarkable 
capacity  for  embolic  dissemination. 

Definition.—: is  malignant  tumour,  the  commonest  of  the  sarcomata, 
which  is  composed  of  spindle-shaped  cells  varying  in  size,  and  con- 


DISEASES    OF    THE    GUMS    AND    JAWS 


335 


taining  one  or  more  nuclei.  It  is  less  malignant  than  the  round- 
celled  varieties,  at  first  may  be  encapsulated  but  later  infiltrate  the 
surrounding  tissues.  The  cells  are  embedded  in  a  scanty  amount  of 
intercellular  material.  The  tumours  may  arise  in  the  periosteum  of 
the  jaws  or  the  alveolo-dental  periosteum,  and  at  times  in  the  dental 
capsule.     Rarely  they  are  endosteal  in  origin. 

Varieties. — (i)  Small  spindle-cells;  (2)  large  spindle-cells. 

Secondary  Changes. — Fibrification,  fatty  degeneration,  small  blood 
cysts,  ossification  and  ulceration  if  the  gingival  tissue  is  involved. 


Fig.   302. — Hard  fibroma  of  the  hard  palate,  showing  the  coarse  nature  of  the 
growth.      Magnified  250  times.     Cf.  Fig.  300. 


HISTOLOGY 

The  cells  are  much  elongated,  with  long  tapering  polar  processes. 
A  supporting  stroma  is  often  indistinguishable,  so  closely  set  are  the 
cells.  There  may  be  two  kinds  of  these,  small  and  large,  as  in  the 
round-celled  sarcomata. 

In  the  former  the  constituent  parts  are  uniform  in  size  and  ap- 
pearance, while  the  latter  display  many  features  of  polymorphism, 
round  and  oval  cells  being  inextricably  mixed  with  the  rest  of  the 
tissues.  A  photograph  of  such  a  tumour,  which,  in  spite  of  due 
surgical  precautions,  constantly  recurred  locally  after  removal,  is 
shown  in  Fig.  303. 


2>2>^ 


THE    ORAL   TISSUES 


The  nuclei  are  usually  ovoid,  with  a  small  amount  of  karyoplasm. 
When  the  cells  are  large,  however,  this  nuclear  network  is  abundant 
and  fully  developed,  and  may  contain  one  or  more  nucleoli.  In 
places,  giant  cells  may  be  produced  by  segmentation  of  the  cell 
nuclei. 

The  new  blood-vessels  are  merely  endothelial  tubes  surrounding 
the  sarcomatous  cells.  The  pre-existent  vessels  of  the  supporting 
reticulum  are  probably  those  arteries,  veins,  and  capillaries  which 
possess  well-defined  walls. 


Fig.   303. — Recurrent  sarcoma  of  the  jaws.      Magnified  250  times. 


(v)  Round-celled  Sarcoma 

Definition. — A  malignant  tumour  which  resembles  in  structure 
most  immature  connective  tissue. 

This  genus  of  tumour  is  of  a  softer  consistency  than  that  just 
described.  It  closely  approaches  the  type  of  embryonic  tissue. 
It  is  more  malignant  than  the  preceding.  Originating  in  the 
periosteum  of  the  bones  of  the  jaws,  it  may  invade  the  antrum  or 
attack  and  absorb  the  alveolar  processes. 

In  this  division  two  varieties  are  also  found,  large  and  small- 
celled.  In  the  former  polymorphous  elements  may  be  discovered: 
epitheloid  and  endotheloid  cells,  arranged  in  localised  masses,  and 
divided  from  one  another  by  a  distinct  stroma,  may  occur,  and  by 


DISEASES    OF    THE    GUMS    AND    JAWS  337 

their  mode  of  arrangement  give  to  this  form  of  tumour  the  name  of 
"Alveolar  sarcomata."  (Billroth.)  These,  endothelial  in  origin, 
ought  really  to  be  classified  amongst  the  endotheliomata. 

It  is  very  difficult  histologically  to  differentiate  between  young 
granulation  tissue  and  small  round-celled  sarcomata.  The  history 
of  the  case  and  the  clinical  evidence  here  weigh  very  heavily  in 
deciding  the  pathology  of  the  growth  and  the  course  of  treatment 
to  be  adopted,  as  well  as  in  the  general  prognosis. 

Secondary  Changes. — Fatty  degeneration  or  minute  haemorrhages. 

(vi)  Giant-celled  Sarcoma 

Definition. — A  malignant  tumour  containing  giant-cells. 

As  has  been  pointed  out,  myeloid  cells  may  occur  at  times  in 
the  large-celled  varieties  of  spindle  and  round-celled  sarcomata. 
But  giant-celled  sarcomata  are  really  those  neoplasms  not  uncom- 
mon about  the  jaws  (especially  the  mandible)  of  children  and  young 
adults,  in  which  giant-cells  are  a  distinguishing  feature  both  with 
regard  to  size  and  number.  They  are  the  least  malignant  of  all 
the  sarcomata. 

Synonym. — "Malignant  'epulis,'  "  or  myeloma. 

Etiology. — These  tumours  arise  probably  either  from  the  peri- 
osteum of  the  jaws  or  the  cancellous  bone  of  their  interiors.  The 
method  of  formation  of  the  large  masses  of  protoplasm  is  obscure. 
Some  of  them  may  possibly  be  regarded  as  phagocytes  (occasionally 
blood  pigments  and  other  chemical  products  may  be  found  enclosed 
in  their  protoplasm) ;  others  possibly  have  their  origin  in  the  fusion 
or  confluence  of  smaller  endothelial  cells. 

Secondary  Changes. — Small  numerous  haemorrhages. 

It  most  frequently  occurs  in  connection  with  bone,  is  of  slow 
growth,  and  seldom  recurs  after  removal,  in  consequence  of  the  fact 
that  it  does  not  invade  the  lymph  nodes  nor  become  disseminated  by 
the  blood  stream.  In  the  maxilla  it  arises  in  the  alveolar  processes, 
or  the  facial  wall  of  the  antrum:  in  the  mandible  in  the  alveolar 
processes,  generally  (in  both  jaws)  in  the  region  of  the  second  pre- 
molar or  first  permanent  molar. 

HISTOLOGY 

Myeloid  sarcoma  consists  of  dense  firm  masses  of  round  or  spindle 
cells  contained  in  a  small  amount  of  fibrous  stroma,  and  possessing 
large  multi-nucleated  cells  in  abundance. 


22^ 


THE    ORAL   TISSUES 


Fig.   304. — Two  myeloid  cells  in  a  myeloid  sarcoma  attached  to  the  periodontal 
membrane  and  bony  socket  of  a  molar.      Magnified  500  times. 


Fig.  305. — The  same,  magnified  750  times. 


DISEASES    OF    THE    GUMS    AND    JAWS 


339 


These  cells  vary  in  shape  in  different  parts  of  the  growth,  and  con- 
tain varying  numbers  of  small  nuclei — as  many  as-  two  or  three 
hundred  have  been  counted — or  a  few  large  nuclei  or  even  one  large 
nucleus,  showing  no  evidence  of  subdivision.  They  may  be  vacuo- 
lated, and  are  usually  surrounded  by  clear  spaces  of  different  width, 
the  result  of  rapid  shrinkage  during  the  fixing  and  hardening  of  the 
soft  tissues  (see  Figs.  304  and  305). 


I 


Fig.  306. — Melanotic  sarcoma.  Stained  with  hsematoxylene  and  eosine. 
Magnified  150  times.  A.  Alveolar  stroma  containing  many  round  and  spindle 
cells;  p.   Pigment  granules  of  melanin. 


(vii)  Melanotic  Sarcoma 

Melanotic  sarcoma  of  the  palate  may  occur  as  a  downward  exten- 
sion from  a  melanotic  sarcoma  of  the  choroid  coat  of  the  eye.  The 
rarest  of  all  forms  of  sarcoma,  it  is  extremely  malignant,  becoming 
rapidly  disseminated  in  the  lungs  and  other  organs. 


340  THE    ORAL    TISSUES 

It  generally  consists  of  small  round  cells  which  contain  pigment 
granules.     Pigment  also  exists  in  the  intercellular  substance. 

(viii)  Endothelioma 

May  occur  in  the  buccal  cavity,  but  is  very  rare.  It  represents 
a  sub-variety  of  the  sarcomata,  but  differs  from  them  both  morpho- 
logically and  histogenetically. 

Thus  the  term  includes  all  neoplasms  which  take  their  origin  in 
endothelial  cells,  either  those  of  the  blood-vessels  of  the  lymphatic 
spaces  or  the  lymphatic  vessels.  It  is  easy  to  confuse  them  with 
the  carcinomata,  which  in  many  ways  they  very  closely  simulate. 

The  endotheliomata  found  in  the  gum  most  probably  originate 
in  the  walls  of  the  blood  or  lymphatic  system. 

HISTOLOGY 

The  bulk  of  the  growth  consists  of  cells,  often  arranged  in  alveoli, 
like  the  alveolar  sarcomata,  columns  of  endothelial  cells — round, 
fiat,  or  cubical  in  shape — which  unite  in  an  irregular  fashion  with 
each  other,  and  nests  of  epitheloid  cells.  A  fair  amount  of  stroma 
of  connective-tissue  fibres  is  present  between  the  cells  of  the  alveoli. 

II.    TUMOURS    OF    THE    COMPLEX    CONNECTIVE    TISSUE    TYPE 

(ix)  Papilloma  of  the  Gum 

GENERAL    CHARACTERISTICS 

Definition. — An  innocent  tumour  of  papilliform  character  confined 
to  the  mucous  membrane. 

Pathology. — This  neoplasm  belongs  to  a  papillary  type  of  growth 
assuming  the  morphological  characteristics  of  villous  excrescences 
and  projecting,  as  a  compound  nodular  mass  above  the  surface  of  the 
gum  or  mucous  membrane  of  the  palate.  It  is  closely  related  to  the 
condylomata,  verruca,  and  villous  growths  of  the  urinary  bladder, 
rectum,  larynx  or  trachea. 

The  papillomata  vary  in  size  and  shape,  but  often  appear  pe- 
dunculated, and  have  a  tuberous  floral  aspect.  Dense  in  consist- 
ency, they  are  devoid  of  tactile  or  painful  sensations,  grow  slowly, 
and  possess  all  the  signs  and  symptoms  of  benign  tumours. 

Two  varieties  exist — hard  and  soft.  Of  these  the  hard  variety 
is  the  only  one  found  in  the  mouth. 


DISEASES    OF    THE    GUMS    AND    JAWS 


341 


Etiology. — The  cause  is  obscure;  but  probably  long-continued 
localised  irritation  is  an  important  factor.  Embryonic  influences 
are  difficult  to  trace. 


HISTOLOGY 


The  epithelium  is  of  the  stratified  squamous  variety.  Very 
abundant,  it  consists  of  many  layers,  and  presents  various  stages  of 
corneous  transformation. 


Fig.   307. — Papilloma  of  the  palate.      Stained  with  Ehrlich's  acid  hasmatoxylene. 
Magnified  45  times. 

In  length,  the  longest  papilla  may  vary  from  1.8  mm.  to  2  mm. 

The  body  of  the  growth  consists  of  dense  connective  tissue  fibres, 
of  which  the  cell  elements  are  similar  to  those  of  the  gum.  There 
is  increase  in  size  and  alteration  in  shape  of  the  ordinary  papillae. 
The  vascular  supply  is  more  abundant  than  usual,  and  the  con- 


342 


THE    OBAL    TISSUES 


stitueni  cells  and  fibres  of  the  part  are  of  a  coarser  nature  than 
normal. 

(x)  HcBmangioma  of  the  Palate 

GENERAL    CHARACTERISTICS 

Definition. — A  tumour  consisting  of  masses  of  blood-vessels. 
Varieties. — Included  under  the  term  angioma  are: 

(i)  Nasvi  or  birth-marks. 

(ii)  Plexiform    angiomata,    or    cirsoid    aneurysms,    com- 
posed of  newly  formed  vessels. 

(iii)  Cavernous  angiomata. 


Fig.  308. — Hemangioma  of  the  palate.  Stained  with  borax-carmine.  Mag- 
nified 30  times.  o.E.  Oral  epithelium;  b.  Connective  tissue  with  blood- 
vessels. 

Of  these,  naevi  may  be  found  on  the  lips;  the  presence  of  plexi- 
form angiomata  in  the  mouth  has  never  been  recorded;  but  cavernous 
tumours  may  occur. 

These  are  made  up  of  communicating  spaces  filled  with  blood  and 
separated  by  connective  tissue  in  greater  or  less  abundance. 

Etiology. — Their  origin  is  unknown. 

HISTOLOGY 
A     cavernous     angioma — hjemangioma — consist     of    numerous 
rounded    or    oval   spaces   enclosed  in  delicate  walls  of  connective 


DISEASES    OF    THE    GUMS    AND    JAWS  343 

tissue,  and  lined  with  endothelium.  The  spaces  are  filled  with  blood 
corpuscles,  while  imbedded  in  the  thin  branching  cohnective  tissue 
fibres  outside  are  some  escaped  leucocytes  and  proliferated  tissue 
cells.  The  vessels  in  places  are  thrombosed,  and  haemorrhages  of 
varying  degrees  of  magnitude  take  place. 

The  surface  is  clothed  with  epithelium,  which  has  undergone  no 
change  from  a  normal  condition. 

The  process  of  phagocytosis,  induced,  in  some  instances  probably, 
by  the  death  of  the  blood  elements  occasioned  either  by  their  escape 
into  the  surrounding  tissues  or  stagnation  in  the  spaces,  has  not  been 
observed  in  any  specimens  under  consideration. 

(xi)  Osteoma 

Definition.— k  connective  tissue  homologous  tumour  arising  only 
in  connection  with  bone,  and  essentially  differing  from  calcification  or 
ossification  of  other  tumours.  Osteomata  may  be  classified  as  cir- 
cumscribed or  diffuse.  The  former -are  found  in  the  mandible,  etc., 
and  the  latter  in  the  maxillary  sinus. 

The  tissue  consists  of  hard  cancellous  bone  (see  Fig.  316). 
Haversian  canals  may  or  may  not  be  present.  Periosteum  surrounds 
the  new  growth. 

III.   EPITHELIAL   TUMOURS 

(xii)  Adenoma 

Definition. — A  tumour  of  the  type  of  epithelial  or  glandular  tissue; 
benign;  only  arises  from  pre-existing  glandular  tissue.  Adenomata 
do  not  secrete,  and  have  no  ducts. 

Varieties.— (i)  Acinous,  (ii)  Tubular.  The  former  are  found, 
amongst  other  places,  in  the  base  of  the  tongue,  the  lip,  the  parotid: 
the  latter  in  the  antrum. 

HISTOLOGY 

Secondary  Changes. — Cystic  degeneration  following  on  mucoid 
softening  and  fatty  degeneration  of  the  epithelium. 

Cylindrical  epithelial  cells  with  a  nucleus  in  the  centre  of  each,  in 
groups,  separated  by  connective  tissue  with  blood-vessels. 

(xiii)  Carcinoma 

Definition. — Carcinomata  are  maUgnant  growths  which  consist  of 
epithelial  cells  contained  in  an  alveolar  stroma,  derived  from  pre- 
existing epithelium. 


344  THE    ORAL    TISSUES 

This  important  group  of  malignant  tumours  is  anatomically 
divided  into  three  classes: — 

1.  Spheroidal-celled, — e.g.,  scirrhus,  medullary. 

2.  Squamous-celled, — epithelioma. 

3.  Columnar    or    cylindrical-celled, — e.g.,    of    the    rectum, 
uterus,  etc. 

Further  sub-divisions,  based  on  pathological  and  clinical  principles, 
are  made. 

Of  these,  however,  only  one  form  need  demand  the  attention  of 
the  dental  surgeon,  viz.,  the  squamous-celled  genus  known  as  the 
epitheliomata. 

These  spring  either  from  the  skin  of  the  lips  or  the  mucous  mem- 
brane of  the  mouth,  which  in  Vol.  I  has  been  described  as  being 
covered  principally  by  stratified  squamous  or  ''pavement" 
epithelium. 

Etiology. — ^Long-continued  irritation  of  the  mucous  membrane 
of  the  gum  or  palate,  due  to  the  presence  of  sharp  edges  of  carious 
teeth,  rough  surfaces  or  margins  of  ill-fitting  dentures,  etc. 

In  the  case  already  quoted  on  p.  268,  the  cause  could,  without 
hesitancy,  be  attributed  to  the  irritation  of  the  epithehal  "rests" 
in  the  periodontal  membrane  due  to  septic  infection  from  the  pulp 
of  a  dead  tooth. 

Pathology. — In  its  earliest  phases  of  development  a  squamous- 
celled  carcinoma  is  either  a  small  superficial  indurated  nodule  on, 
or  a  fissure  in  the  gum.  It  very  rapidly  becomes  ulcerated,  and  then 
there  appears  an  excavation  whose  edges  are  raised,  irregular  in 
outhne,  everted,  and  hard  in  consistency,  whose  base  is  indurated 
and  irregular,  whose  environing  structures  are  infiltrated  with  epi- 
thelial collections  and  small- celled  masses.  The  lymphatics  which 
drain  the  part,  infect  the  lymphatic  glands,  which  become  enlarged 
and  hard,  and,  later  on,  fixed  to  the  surrounding  tissues. 

Secondary  Changes. — Ulceration  of  the  surface. 

HISTOLOGY 

The  substance  of  an  epithelioma  is  composed  of  flat,  round, 
or  polygonal  cells  of  varying  size,  arranged  in  alveoli,  and  imbedded 
in  a  connective-tissue  stroma  more  or  less  rich  in  infiltrated  cells. 

Two  portions  of  the  growth  may  be  recognised  and  having  dif- 
ferent characters,  clearly  distinguished. 

In  the  younger  developing  part  the  cells  are  round  and  the  stroma 


DISEASES    OF    THE    GUMS    AND    JAWS 


345 


Fig.  309. — Epithelioma  of  the  palate.  Prepared  by  fixing  and  hardening  in 
alcohol  and  formalin.  Magnified  45  times.  Shows  ulcerated  surface,  o.e. 
Oral  epithelium;  e.  Columns  of  epithelium  extending  irregularly  into  the  sub- 
mucous tissue. 


O  E 


O  E 


Fig.  310. — Another  portion  of  the  same.  Shows  the  epithelial  margin  of 
the  ulcer  depicted  in  the  previous  figure,  o.e.  Oral  epithelium;  s.  Submucous 
tissue. 


346 


THE    ORAL    TISSUES 


extremely  cellular;  in  the  older  there  is  a  tendency  for  the  epithelial 
cells  to  become  flattened  and  to  display  in  places  corneous  or  kera- 
tinous  changes  as  in  the  superficial  cells  of  the  stratum  corneum. 
Some  cells  show  evidences  of  great  activity  in  the  shape  of  mitosis. 
The  epithehal  columns  which  have  pierced  the  basement  mem- 
brane and  have  invaded  the  sub-epithelial  tissues  are  irregular  in 
outline,  generally  being  round  or  oval.  They  are  discontinuous  with 
the  surface  epithelium,  and,  cut  off  from  the  oral  cells,  become 
isolated  and  form  alveoli  or  islands  of  epithelium  separated  by  a 


Fig.  311. — Squamous-celled  carcinoma  of  the  palate.  Prepared  by  har- 
dening in  alcohol.  Stained  with  hEematoxylene.  c.  Cell  nest.  Magnified  50 
times. 


stroma  which  contains  imperfectly  developed  connective  tissue 
fibres  and  small-celled  infiltration. 

In  the  epithehal  prolongations  into  the  sublying  tissues  and  in  the 
alveoli  are  often  found  collections  of  cell  nests. 

Cell  nests  are  concentrically  arranged  whorls  of  cells  gathered 
around  a  homogeneous  non-nucleated  body  or  group  of  bodies  which 
consist  of  keratinous  material.  This  cornification  progresses  from 
within  outwards,  the  change  represented  by  the  cells  being  crescentic, 
cubical  and  cylindrical  respectively. 

Cell  nests  are  only  pathognomonic  of  epitheliomata  when  they 


DISEASES    OF    THE    GUMS    AND    JAWS 


347 


are  found  in  islands  imbedded  in  the  depth  of  the  tissues  far  from 
the  surface  with  which  they  are  discontinuous. 

Some  pathologists^  believe  that  in  the  concentric  bodies  may  be 
found   most   pronounced    evidences    of   nuclear   and   protoplasmic 


c  T 


Fig.  312. — A  gumma  of  the  mucous  membrane  of  the  palate.  Stained  with 
heematoxylene.  Magnified  35  times,  g.t.  Granulation  tissue  on  free  surface; 
F.  Fatty  degeneration;  c.t.  Connective  tissue  of  the  palate.  B.  Blood-vessel 
cut  longitudinally. 

necroses,  "together  with  the  peculiar  process  of  inclusion  of  one 
epithelial  cell  by  another,  and  an  active  invasion  of  leucocytes,  some 
of  which  are  degenerated  and  others  apparently  engaged  as 
scavengers  to  devour  the  detritus  resulting  from  the  necrotic 
processes." 

1  Hektoen  and  Riesman.     "A  Text-Book  of  Pathology,"  Vol.  T.,  [).  218,  1901. 


348 


THE    ORAL    TISSUES 


Syphilis 

This  disease  may  affect  the  gums  and  buccal  cavity  in  one  of 
several  ways. 

Hard  chancres  of  the  lips  are  far  from  uncommon:  and  it  is  possible 
for  these  primary  sores  to  occur  also  on  the  tongue  and  gums. 


CT 


FiG.   313. — The    same   as   the   preceding.     Lettering    as  before.      Magnified   50 

times. 

A  syphilitic  stomatitis  often  develops  in  the  secondary  and  ter- 
tiary stages  of  the  infection,  and  gummata  may  be  seen  occasionally. 

The  accompanying  photomicrographs  show  gummatous  infil- 
tration of  the  mucous  membrane  of  the  palate. 

A  gumma  is  a  chronic  inflammation  which  leads  to  the  production 
of  granulation  tissue.  Varying  in  size,  these  lesions,  as  is  seen  in 
Fig.  313,  are  intimately  associated  with  the  surrounding  tissues. 


DISEASES    OF    THE    GUMS    AND    JAWS  349 

They  may  become  absorbed;  or  remain  in  situ  indefinitely  without 
any  signs  of  retrogressive  changes;  but  they  often  caseate,  break 
down,  and  form  a  deep  punched-out  ulcer. 

A  gumma  consists  of  a  degenerated  central  part,  an  intermediate 
zone  of  small-celled  infiltration,  and  a  peripheral  tract  or  belt  of 
rapidly  developing  blood-vessels  ramifying  in  a  cellular  matrix. 
Fatty  degenerative  changes  are  most  frequently  observed,  and,  no 
doubt,  are  occasioned  by  the  cutting  off  of  the  nutritive  supply  of  the 
most  central  portions,  through  changes  in  the  vessel  walls,  which 
induce  either  complete  thrombosis  or  diminution  in  the  calibre  of 
the  vessels. 


OF  THE   MUCOUS  LINING  OF  THE  MAXILLARY  SINUS 

Inflammation  of  the  mucous  membrane  of  the  antrum  is  similar 
to  that  of  other  soft  tissues.  Details  need  not  be  recapitulated. 
Sufl&ce  it  to  say  that  the  cihated  epithelium  becomes  rapidly  de- 
generated and  completely  disorganised.  The  cell  infiltration  is 
carried  on  to  an  enormous  extent,  the  tissue  greatly  swollen  and 
thickened,  and  if  not  suppurative,  undergoes  fatty  and  mucoid 
changes  (see  Fig.  314). 

Spheroidal-celled  carcinoma  may  occur.  The  photo-micrographs 
are  from  specimens  given  to  the  author  by  Sir  Francis  Farmer. 
Its  chief  characteristics  are  the  following: — The  cells  are  spheroidal 
in  shape,  and  are  exceedingly  hable  to  undergo  fatty  degeneration; 
they  are  grouped  into  large  soft  alveoli;  the  separating  stroma  is 
very  variable  in  amount,  and,  when  scanty,  is  devoid  of  contractile 
properties.  Medullary  carcinomata  are  noted  for  their  abundant 
vascular  supply,  in  consequence  of  which  haemorrhages  are  very 
frequent  in  the  substance  of  the  growth. 


OF    THE   JAWS 

The  external  and  internal  plates  of  the  alveolar  processes  of  the 
jaws  may,  at  times,  be  subject  to  the  formation  of  osseous  growths 
commonly,  though    not  always  correctly,  spoken  of  as  exostoses. 

Etiology. — Exostoses  are  very  often  regarded  in  the  light  of 
tumours,  i.e.,  non-inflammatory  growths.  But  many  of  the  hard 
nodular   periosteal    swellings  of  the  jaws  may  be  considered  with 


350 


THE    ORAL    TISSUES 


E  T 


Pig.  314. — Chronic  inflammation  of  the  mucosa  of  the  antrum  of  Highmore. 
Magnified  230  times.  E.  Ciliated  epithelium:  ex.  Sub-epithelial  tissue  ^in- 
filtrated with  inflammatory  cells  and  products.  (From  a  specimen  given  to  the 
Author  by  Dr.  Cuthhert  Lockyer.) 


Pig.  315. — Hard   spheroidal-celled    carcinoma  of   the  mucosa  of  the  antrum  of 
Highmore.      Magnified  230  times. 


DISEASES    OF    THE    GUMS    AND    JAWS 


351 


equal  satisfaction  as  originating  in  the  form  of  inflammatory  osteo- 
phytes or  hyperostoses  comparable  to  osteitis  in  other  parts  of  the 
body.  Thus  a  distinction  should  be  made  between  circumscribed 
osteomata  and  exostoses.  When  occurring  in  the  mandible  the 
former  most  likely  are  due  to  certain  rare  developmental  anoma- 
lies of  Meckel's  cartilage;  when  elsewhere,  the  latter  probably 
arise  either  from  the  periosteum  of  the  jaws  or  of  the  teeth.     In  the 


Pig.  316. — Endosteal  osteoma  of  the  mandible.     Stained  with  hsematoxylene. 
Magnified  150  times,     b.  Bone;  M.   Degenerated  medullary  tissue. 

first  instance,  exostoses  may  be  due  to  a  localised  periosteal  depo- 
sition of  new  bone  analogous  to  the  nodes  produced  by  syphilis, 
often  observed  on  the  surface  of  the  tibiae,  or,  as  Turner  believes, 
the  outcome  of  "pyorrhoea  alveolaris." 

Pathology. — Bony  tumours  generally  appear  as  sessile  sweUings 
of  a  dense  hard  character,  covered  with  thin  mucous  membrane 
which  has  a  normal  aspect.  They  are  painless,  slowly  growing 
tumours,  and  generally  easily  diagnosed. 


352 


THE    ORAL    TISSUES 


HISTOLOGY 


The  microscopical  structure  is  interesting.  An  external  shell  or 
crust  of  compact  covers  a  circumscribed  nodule  of  cancellous  bone, 
which  simulates  very  exactly  the  normal  types  of  osseous  tissue. 


Tumours 

The  tumours  most  frequently  associated  with  the  maxilla  and 
mandible  are  cystic  or  solid.  The  former  comprise  dental  cysts, 
epithelial  and  follicular  odontomes,  and  mucous  retention  cysts  (ade- 


PiG.  317. — Adenoma  of  the  maxillary  sinus  arising  from  the  periodontal  mem- 
brane of  a  third  maxillary  molar.  Stained  with  hasmatoxylene.  Magnified  45 
times.  D.  Dentine;  a.  Adenoma;  s.  Soft  tissue  attached  to  the  root  of  the 
tooth. 

nomata)  of  the  antrum,  &  c. ;  the  latter,  growths  having  the  structure 
of  fibrous  tissue,  mucous  tissue,  cartilage  (enchondromata)  and  bone 
(osteomata  and  diffused  and  general  diffused  hyperostoses).  Sar- 
comata and  carcinomata,  too,  unfortunately,  are  far  from 
uncommon. 

It  is  unnecessary  to  enter  into  further  details  of  these  various 
new  formations,  but  brief  reference  to  one  of  them  may  be  mentioned. 


DISEASES    OF    THE    GUMS    AND    JAWS 


353 


Cystic  Adenoma  of  the  Antrum 

Cystic  degeneration  of  an  adenoma  of  the  antrum  of  the  left 
superior  maxilla,  occurring  in  a  woman  aged  twenty- five  is  illustrated 
in  Figs.  317  and  318.  It  had  been  occasioned  entirely  by  the  malpo- 
sition and  fruitless  efforts  at  eruption  of  the  third  molar.  The  peri- 
odontal membrane  of  this  tooth  had  stimulated  the  mucous  antral 


Fig.  318. — Cystic  degeneration  of  the  adenoma  of  preceding  figure.  Stained 
with  hsematoxylene  and  eosine.  Magnified  250  times,  e.  Glandular  epithe- 
lium; C.  Cyst  filled  with  albuminoid  material;  s.  Stroma  of  tumour. 

glands  to  enlarge.  The  adenoma  filled  up  the  greater  portion  of 
the  upper  part  of  the  antrum.  In  places  the  bony  wall  had  become 
absorbed  and  the  new  growth  extended  through  the  soft  tissues  and 
mucous  membrane  of  the  palate  in  the  neighbourhood  of  the  molars. 
In  breaking  down,  a  deep  punched-out  ulcer  was  produced,  which 
closely  resembled  a  breaking  down  syphilitic  gumma,  or  an 
epithelioma. 
23 


CHAPTER  XIV 
DISEASES  OF  THE  ORAL  MUCOUS  MEMBRANE 

Microscopical   Elements  in:     (i)    Inflammation;    (ii)    Tubercu- 
losis; (iii)  Malignant  degeneration. 


Stomatitis 

Definition. — Inflammation  of  the  mucous  membrane  of  the  oral 
cavity,  including  that  of  the  lips,  cheeks  and  alveolar  process  collect- 
ively or  severally. 

Differential  Diagnosis 


Variety- 


Causes 


Symptoms 


Diagnosis 


Terminations   or 
complications 


Simple 

catarrhal 


(i)    Local:    Faulty 
oral  hygiene,  tar- 
tar,   use   of    vul-, Mucous  mem- 
canite    dentures,     brane        swollen, 
mouth  breathing,!   epithelium  thick- 
chemical  irritants, '   ened,       anorexia. 


abuse  of  tobacco, 
etc. 

(ii)  General:  Dys- 
pepsia, gastritis, 
gastric  ulcer, gout, 
diabetes,  chronic 
nephritis,  infec- 
tious fevers,  iod- 
ism,  etc. 


foetid  breath,  etc. 
Much  mucous  se 
cretion. 


Favourable. 


2.  Herpetic 


Formation  of  vesi-  Mouth   dry.      Re- 
Catarrh   and   dys-:   cles    which    soon    moval  of  epithe-  Quickly  subsides, 
pepsia.  rupture  and  leave    lium     accompan- 

scabs.  ied  with  pain  and 

haemorrhage. 


3.  Aphthous 


Oidium  albicans. 


Curdy,  easily-de- 
tached, white 
patches. 


Mouth  always 
moist,  epithelium 
easily  peeled  off. 


May  be  fatal 
through  diarrhoea 
and  septic  ab- 
sorption. 


4.  Ulcerative 


Dyspepsia,  local 
irritation,  defec- 
tive oral  hygiene. 


Grey  sloughs,  foul 
breath,  gums  red 
and  swollen. 


Favourable. 


S.  Syphilitic 


Secondary 
Tertiary. 


and 


Symmetrical:  con- 
dylomata and 
mucoustubercles, 
gummata. 


6.   Mercurial 


Abuse  of  mercury. 


Foul  breath,  swol- 
len gums  and 
tongue,  profuse 
salivation,  swell- 
ing of  parotid 
and  submaxillary 
glands.  Loosen- 
ing of  teeth. 


Gangrenous  ulcer- 
ation; extensive 
destruction  of 
tissues,  and  per- 
haps necrosis  of 
bone. 


7.  Gangrenous 
or  Cancrum 
oris 


Capillary     throm- 
bosis    in     cheek, 
perhaps    due    to 
Lingard's  bacil- 
lus. 


Foul  breath,  great 
tenderness  of 

parts,  black  in- 
durated slough 
on  cheek,  exten- 
sive sloughing. 


Toxsemia,  septi- 
caemia, bronchi- 
tis and  pneu- 
monia. 


354 


DISEASES    OF    THE    ORAL    MUCOUS    MEMBRANE 


355 


Varieties.- — Herpetic,  aphthous,  catarrhal,  syphilitic,  ulcerative, 
mercurial,  and  gangrenous. 


HISTOLOGY 


The  pathological  changes  occurring  in  the  tissues  are  similar  in 
all  respects  to  those  observed  elsewhere.  They  do  not  require  a 
special  description. 


Fig.  319. — Tubercular  nodule  in  mucous  membrane  of  cheek.  Stained  with 
hsematoxylene  and  eosine.  Magnified  250  times.  O.E.  Oral  epithelium;  G. 
Giant  cells;  e.   Epitheloid  and  round  cells;  B.   Blood-vessel. 


Tuberculosis 

Tuberculosis  occurring  in  the  mouth  is  at  times  of  primary  origin. 
More  often,  however,  it  follows  laryngeal  or  pulmonary  tuberculosis. 

Situation. — It  is  seen  most  frequently  on  the  dorsum  near  the 
tip  of  the  tongue,  on  the  soft  palate,  on  the  mucous  membrane  of 
the  cheeks  and  on  the  surface  of  the  tonsils. 


356  THE    ORAL    TISSUES 

Origin. — It  begins  as  a  small  superficial  nodule,  and  soon  breaks 
down  and  produces  an  irregular  ulcer  with  infiltrated  edges. 

HISTOLOGY 

A  typical  tubercle  consists  of  many  newly  developed  cellular 
elements.  In  its  centre  are  found:  (i)  giant  cells,  two  or  more  in 
number,  consisting  of  granular  cytoplasm  with  many  peripherally- 
arranged  nuclei.  In  and  around  these  cells  the  Bacillus  tuberculosis 
can  be  demonstrated  by  special  staining.  Surrounding  the  giant 
cells  are  (ii)  numerous  endothelial  cells — oval,  mononuclear  bodies 
about  lo/x  to  15^1  in  diameter,  (iii)  External  to  these  are  many 
round  cells  similar  to  lymphocytes  from  which  they  are  probably 
derived. 

The  accompanying  photomicrograph  may  be  considered  to  be 
fairly  representative  of  the  ordinary  type  of  tubercular  nodule 
found  in  the  mucous  membrane  on  the  surface  of  the  voluntary 
muscle  fibres  of  the  cheek.     (Fig.  319). 

MALIGNANT    DEGENERATION 
INTRODUCTORY 

Possessing  no  ordinary  degree  of  practical  utility,  or  of  interest, 
for  the  modern  dental  surgeon  as  does  a  study  of  the  degenerative 
conditions  which  may  affect  the  root  membrane  of  the  teeth  of 
man — one  of  which  formed  the  subject  of  Chapter  XII — it  will 
doubtless  be  readily  conceded  that  a  condition  which  must  engage 
the  attention  of  the  dermatologist  and  oral  surgeon,  as  well  as 
of  the  general  student  of  this  volume,  is  of  necessity,  and  by  vir- 
tue of  its  larger  bearing  on  surgery  and  on  the  principles  of  life  and 
death,  far  profounder  in  its  importance  and  vaster  in  its  clinical 
and  pathological  significance.  Such  an  one  is  that  type  of  degen- 
eration about  to  be  described. 

The  former: — fibroid  degeneration  of  the  periodontal  membrane — 
having  a  mesodermic  derivation,  is  a  local  manifestation  of  a  be- 
nign condition  which,  per  se,  remains  always  benign;  the  latter, 
ectodermic  in  origin,  a  local  manifestation  of  a  benign  condition 
which,  as  will  be  presently  seen,  may  become  malignant:  the  first 
a  product  and  an  accompaniment  of  senility;  the  second,  of  youth  or 
middle  age;  the  one  a  common  termination  of  a  common  affection, 
the  other  an  unusual  termination  of  a  constantly  occurring  neoplasm. 


DISEASES    OF    THE    ORAL    MUCOUS    MEMBRANE  357 

A  similar  type  of  degeneration,  it  is  perfectly  safe  to  say,  has  hitherto 
never  been  described  as  affecting  the  mouth  and  its  contents. 

The  mucous  membrane  of  the  oral  cavity  is  usually  very  tolerant 
of  the  conditions  to  which  it  is  subject  as  a  consequence  of  injury 
by  friction  from  foreign  bodies  placed  upon  it.  It  may,  however^ 
become  pathologically  affected  and  present  a  mottled  appearance, 
or  be  covered  by  areas  of  tissue  which  look  like  dried  blood-clot. 
Areas  may  remain  for  years  unchanged,  or  if  inflamed,  may 
break  down  and  ulcerate  or  undergo  mahgnant  changes.  Such 
conditions  should  always  be  regarded  with  suspicion,  and  diagnoses 
made  between  dental,  dyspeptic,  tubercular  and  malignant 
ulcerations. 

A  precancerous  condition  as  observed  on  the  surface  of  a  pedun- 
culated fibroma  may  now  be  described. 

HISTOLOGY 

It  will  be  convenient,  in  the  first  place,  in  detailing  the  minute 
anatomical  appearances,  which  to  the  pathologist  cannot  fail  to  be 
of  the  greatest  interest,  to  use  the  somewhat  arbitrary,  artificial 
divisions  adopted  by  microscopists  of  the  present  day,  as  applied 
to  the  epidermal  covering  of  the  skin  and  certain  mucous  mem- 
branes of  the  body.  The  histo-pathology  may  therefore  be  con- 
sidered under  the  headings  of — 

(i)  Changes  in  the  stratum  corneum  including  the  stratum  lucidum 
and  the  stratum  granulosum; 

(ii)   Changes  in  the  stratum  mucosum; 

(iii)  Changes  in  the  sub-epithelial  tissue  or  the  cutis  vera. 

(i)  Changes  in  the  Stratum  Corneum 

The  stratum  corneum  extends  over  four-fifths  of  the  periphery 
of  the  growth;  where  deficient,  there  is  no  differentiation  of  squamous 
stratified  and  columnar  cells.  But  this  layer  presents  many  de- 
partures from  the  normal  type.  In  some  places  it  and  the  contiguous 
strata  are  insensibly  merged  into  one  another;  in  others,  the  former 
is  sharply  defined  (Fig.  320),  and  then  shows  as  an  unusually  thin 
band  of  flat,  narrow,  stratified  corneous  cells  with  elongated  planary 
nuclei  whose  karyoplasm  is  indistinguishable  and  structureless. 
There  is  a  marked  tendency,  here  and  there,  toward  desquamation; 
and  the  free  surface  is  partially  covered  with  layers  of  keratin  or 


358 


THE    ORAL    TISSUES 


kerato-hyalin  material,  which  presents  either  as  a  mass  of  tiny 
granules  or  a  denser,  more  homogeneous,  partially  detached,  ground- 
glass-like  matrix.  Polychrome  methylene  blue  rendered  the  con- 
tents of  these  cells  and  those  of  the  stratum  granulosum  very 
prominent,  and  accentuated,  by  means  of  its  chemical  affinities,  the 
presence,  in  places,  of  flakes  of  eleiden,  (Ranvier)  or  kerato-hyaline. 
Fig.  322  shows  that  in  places  these  superficial  layers  penetrate  almost 
to  the  corium  of  the  fibroma. 


s  c 


Fig.  320. — Degenerated  epithelium  on  surface  of  fibroma.  Stained  with  poly- 
chrome methylene  blue  and  eosine.  s.C.  Line  of  demarcation  between  superficial 
strata  and  stratum  mucosum;  d.  Ballooned  cells  containing  kerato-hyaline;  E. 
Epithelial  cells  of  a  less  degenerate  type;  c.  Connective  tissue  fibres  and  cells  com- 
prising the  substance  of  the  fibroma;  i.p.  Normal  character  of  interpapillary 
process  of  dermis.      Magnified  60  diameters. 


Particularly  striking  are  irregularly  arranged  patches  of  these 
degenerated  cells;  they  appeared  in  every  section.  The  cell  wall 
had  apparently  become  grossly  distended  (ballooning)  by  retrogres- 
sive changes  occurring  within  it  (Figs.  321  and  324).  The  nuclei 
in  many  cases  are  absolutely  destroyed;  the  spongioplasm  had 
disappeared,  and  the  hyaloplasm,  which  in  normal  young  cells 
constitutes  the  greater  relative  amount  of  the  protoplasm,  had 
evidently  become  converted  into  masses  of  keratinized  material 
which  in  vertical  sections  of  the  epithelium  often  filled  the  whole 
of  the  ballooned  cell  and  often  produced  a  meniscus-like  body,  the 
open  space  of  which  was  invariably  situated  at  the  peripheral  portion 


DISEASES    OF    THE    ORAL    MUCOUS    MEMBRANE 


359 


of  the  cell,  and  sometimes  was  empty  but  at  others  partially  filled 
with  granular  detritus  (Fig.  321).  These  patches  extend  some 
distance  toward  the  centre  of  the  fibroma  (Figs.  325  and  326); 
and  the  epidermal  cells  were  simultaneously  proliferating  inward. 

(ii)  Changes  in  the  Stratum  Mucosum 

A  little  lower  down,  and  nearer  to  the  rete  mucosum  or  Malpighii, 
the  cells  are  more  normal  in  shape  and  size.     The  greater  number 


Fig.  321. — To  show  minuter  details  of  epithelium  stained  as  in  preceding.  K. 
Meniscus  of  kerato-hyaline  material;  G.  Granular  type  of  kerato-hyaline  material 
on  free  surface;  N.  Nucleus  lying  in  a  clear  space;  s.  Inter-epithelial  space  devoid 
of  "prickles."      Magnified  240  times. 

are  "prickle"  cells;  but  many  have  no  intercellular  bridges  and 
are  not  separated  by  interepitheUal  channels.  The  majority  of  the 
"prickle"  cells  exhibit  their  nuclei  lying  in  a  clear,  narrow  space 
(Fig.  321).  Perhaps  the  greatest  interest  centres  in  these  nuclei. 
All  changes  and  rearrangements  in  their  karyoplasm  can  be  noticed. 
The  majority  show  them  in  a  "resting"  stage,  but  the  chromosomes 


360 


THE    ORAL    TISSUES 


while  large  in  size  seem  very  few  in  number — a  condition  known  as 
hypo-chromatosis.  On  the  other  hand,  many  of  the  changes  due 
to  the  process  of  mitosis  are  observed  and  the  figures  well  exhibited 
in  the  haematoxylene-stained  sections.  Those  treated  by  the  Van 
Gieson  method  are  not  so  brilliant. 

Most  of  the  changes  familiar  to  the  histologist  and  pathologist 
can  be  detected.  Thus,  typical  heterotype  amphiasters,  ring 
chromosomes  and  centrosomes,  and  many  instances  of  asymmetric 


Fig.  322. — Same  as  preceding,  staining  and  magnification  similar.  K. 
Kerato-hyaline  matrix;  s.c.  Superficial  degenerated  stratum  of  cells;  s.G.  Stratum 
mucosum  (degenerated). 


mitoses  occur.  There  are  slight  evidences  of  karyoclasis  and  karyo- 
lysis,  but  no  vacuolation  of  the  nuclei,  though  the  cells  themselves 
are  certainly,  generally  speaking,  undergoing  hydropic  degeneration.^ 
Darier's  '^coccidia"  and  typical  myeloid  cells  are  also  present,  but 
not  frequent — at  least  bodies  resembling  them  appear  to  exist 
scattered  about  in  places. 

Equally  important  with  the  above  metamorphoses  are  the  presence 
of  the  typical  cell-nests  of  the  squamous  carcinomata.     A  few  are 

1  Delafield  and  Prudden,  Pathology,  1901. 


DISEASES    OF    THE    ORAL    MUCOUS    MEMBRANE 


361 


discerned  near  the  deepest  portion  of  the  rete  mucosum,  and  are 
unduly  large,  and  form,  as  seen  in  Fig.  327,  a  striking  feature  of  the 
sections. 

The  deHcate  basement  membrane  which  supports  the  rete 
Malpighii  is,  generally  speaking,  extremely  irregular  in  outhne 
(Figs.  328  and  329).     The  columnar  epithehal  cells  situated  upon  it 


sc 


SG 


Fig.  323. — Surface  of  fibroma.  Stained  with  h^matoxylene  and  cosine,  s.c. 
Superficial  strata  of  a  fairly  normal  character;  s.G.  Stratum  mucosum  with 
oedematous  epithelium;  p.  Epithelial  cells  proliferating  inward,  and  breaking 
through  the  normal  basement  membrane;  f.  Connective  tissue  of  fibroma;  s. 
Small  round-celled  infiltration.      Magnified  50  diameters. 

appear  to  be  fairly  regular  in  shape,  and  to  show  few  evidences  of 
degeneration  or  oedema.  But  the  uniformity  of  outline  of  the  base- 
ment membrane  repeatedly  and  greatly  departs  from  its  usual 
foldings,  and  the  interpapillary  spaces  are  exceedingly  irregular. 

In  that  portion  of  the  periphery  of  the  growth  where  the  strata 
corneuni,  lucidum,  and  granulosum  are  absent,  the  epithelial  cells 
are  all  more  or  less  (jedematous  (Fig.  329),  and,  briefly,  exhibit  signs 
of  a   condition   corresponding   to  eczema  of   the   skin.     They  are 


362 


THE    ORAL   TISSUES 


swollen,  rounded,  greatly  multiplied,  and  tend  to  an  anomalous 
degeneration,  being  absolutely  devoid  of  intercellular  bridges.  As 
a  result  of  the  colliquative  degeneration,  vesiculation  has  slightly 
occurred;  and  there  are  also  many  migratory  cells,  etc.  Their 
depth  from  the  surface  does  not  modify  these  changes  (Fig.  330). 
The  process  of  mitosis  is  with  difficulty  made  out  in  these  situations, 
though  there  is  no  doubt  that  it  is  taking  place,  and  that  some 
proliferation  and  growth  of  the  epidermis  accompanies  it. 


Fig.   324. — Large  patches   of   ballooned   epithelium  in  degenerated  cedematous 
tissue.     Stained  with  haematoxylene.      Magnified  250  diameters. 


(iii)  Changes  in  the  Cutis  Vera 

Here  the  papillae  are  seen  to  be,  in  parts  of  the  fibroma,  very 
irregular,  as  already  indicated.  A  noticeable  condition  is,  however,, 
the  small  round-celled  infiltration  which  has  been  associated  with 
the  cytological  metamorphoses.  In  the  neighbourhood  of  the  cell 
nests,  in  the  most  irregularly  shaped  interpapillary  processes,  and 
beneath  the  cedematous  surface  this  infiltration  is  most  marked. 
The  cells  themselves  are  largely  of  the  Unna's  plasma-cell  type, 
mixed   with    a   few   leucocytes    (polymorpho-nuclear   neutrophiles 


DISEASES    OF    THE    ORAL    MUCOUS    MEMBRANE 


363 


Fig.  325. — Another  degenerated  patch  showing  its  superficial  position; 
stained  with  hsematoxylene.  d.  Cluster  of  ballooned  cells;  e.  Irregular  outline 
of  basal  layer  of  epithelium.      Magnified  45  diameters. 


Fig.  326. — Similar  to  preceding,  but  cxhiLiLiiiM  Llic  various  stages  in  the  process 
of  formation  of  the  ballooning  of  the  cells.  Stained  with  ha^matoxylene  and  eosine. 
D.  Cells  of  a  fairly  normal  character,  but  passing,  on  the  left,  to  the  condition 
which  is  at  its  highest  point  of  development  at  k;  e.  Epithelium  of  stratum 
mucosum.      Magnified  50  diameters. 


364 


THE    ORAL    TISSUES 


and  lymphocytes)  and  some  eosinophiles  and  connective  tissue 
nuclei  and  the  "mast  cells"  of  Ehrhch.  In  addition  there  is  an 
abundant  blood  supply. 

ETIOLOGY 

It  is  now  permissible,  necessary,  and  logically  sequential  that  an 
inquiry  should  be  instituted  with  regard  to  the  theory  concerned 


Fig.  327. — Cell  nest  at  base  of  epithelial  column.  Stained  with  haematoxylene 
and  eosine.  e.  Epithelium  of  stratum  mucosum;  e.g.  Cell  nest  showing  corneous 
character  of  the  central  portion;  k.  Epithelial  cells  undergoing  mitosis;  nuclei 
displaying  asymmetric  mitoses;  L.  Polymorpho-nuclear  leucocyte  in  small-celled 
infiltration.      Magnified  250  diameters. 

in  the  causation  of  the  changes  already  described,  and  an  endeavour 
made  to  bring  them  into  line  with  those  of  modern  research.  It 
may,  however,  be  stated  at  the  outset  that  many  difficulties  beset 
this  work.  The  recording  of  clinical  histories  and  the  describing  of 
macroscopical  and  microscopical  anatomy  are  accomplished  with 
facihty  and  some  degree  of  certainty;  not  so  when  attempts  at 
etiology  are  undertaken. 

The  exciting  cause  (or  causes)  of  cancer  has  for  generations  per- 


DISEASES    OF    THE    ORAL   MUCOUS    MEMBRANE 


365 


plexed  the  minds  of  men,  and  today  there  is  probably  no  one  de- 
partment of  medical  science  which  has  more  strenuous  followers, 
bacteriology  and  therapeutics  not  excepted.  It  would  not  be  germane 
to  the  scope  and  intention  of  this  chapter  if  the  various  questions 
relative  to  it  were  discussed.  It  must  be  sufhcient  if  allusion  is 
very  briefly  made  to  the  latest  opinions  of  authoritative  and  com- 
petent witnesses,  and  these  suggestions  applied  to  the  present  case. 


Fig.  328. — 

eosine. 


Irregularity  of  epithelial  surface.     Stained  with  hsematoxylene  and 
E.   Epithelium;  F.   Tissue  of  fibroma.      Magnified  45  diameters. 


The  cUnical  notes  do  not  in  any  way  account  for  the  presumably 
sudden  assumption  on  the  part  of  an  innocent  tumour  of  malignancy. 

Physical  and  chemical  lesions  seem  to  be  at  once  eUminated  as 
affording  the  least  possible  clue.  There  was  no  apparent  source  of 
irritation  or  traumatism  as  occurs  unmistakably  in  mammary 
scirrhous  carcinoma,  or  labial  epithelioma,  or  "chimneysweep's" 
cancer,  and  the  predisposing  factor  of  age  can  also  be  put  out  of  court. 
Sections  were  stained  specially  to  discover  if  bacterial  or  protozoan 
or   blastomycetic   infection   had   occurred — with   negative   results; 


366 


THE    ORAL   TISSUES 


although  it  is  most  obvious  that  the  skin  and  mucous  membranes 
generally  must  be  easily  subject  to  invasion  by  the  micro-organisms 
which  they  so  constantly  harbour. 


'   J 


ft^ 


Fig.  329. — Surface  of  fibroma  at  junction  of  eczema-like  epithelium,  with  the 
epithelial  layers  of  preceding  sections,  s.  Epithelium  similar  to  that  in  preceding 
figure;  e.  (Edematous  cells  with  no  superficial  strata,  and  extending  in  irregular 
columnar  formation  into  the  substance  of  the  fibroma.  The  rapidly  growing 
epithelium  and  the  round-celled  infiltration  of  the  sub-epithelial  tissue  are  shown. 
Magnified  45  times. 

Serious  and  continuous  consideration  of  the  clinical  history,  com- 
bined with  the  patho-histology,  would  seem  to  argue  against  Cohn- 
heim's  embryonal  theory,  which  was  originally  introduced  in  1882, 
and  has  been  recently  revived  by  Sir  Henry  Morris,  who,  in  the  Brad- 
shaw  Lecture  of  the  Royal  College  of  Surgeons  of  England,  in  1903, 


DISEASES    OF    THE    ORAL   MUCOUS    MEMBRANE 


367 


Strongly  advocated  the  views  therein  promulgated.  The  mechanical 
isolation  hypothesis  of  Ribbert,  as  well  as  the  anaplasic  theory  of 
Hausemann^  would  also  appear  to  fall  to  the  ground. 

But  there  is  apparently  nothing  to  refute,  nor,  be  it  remarked,  to 
absolutely  verify,  the  quarter-of-a-century-old  doctrines  of  Thiersch 
and  Waldeyer,  who  believe  that  cancer  cells  take  their  origin  from 
altered  pre-existing  epithelial  cells. 


R  r 


Fig.  330. — Dense  cell  infiltration  of  dermal  tissue  at  base  of  epithelial  column. 
E.  Stratum  mucosum;  R.  Cellular  infiltration  in  connective  tissue.  Magnified 
210  times.  ' 

In  a  most  instructive  paper  presented  to  the  Royal  Society  of 
London,  in  December  1903,  by  Messrs.  Bretland  Farmer,  Moore, 
and  Walker,  entitled  "On  the  Resemblances  Exhibited  Between  the 
Cells  of  Malignant  Growths  in  Man  and  Those  of  Normal  Repro- 
ductive Tissues,"  the  following  sentence  occurs: "  In  a  typical  example 

'See  Bashford  and  Murray,  "The  Significance  of  the  Zoological  Distribu- 
tion, the  Nature  of  the  Mitoses,  and  the  Transmissibility  of  Cancer,"  Proceed- 
ings of  Ihe  Royal  Sociely,  vol.  Ixxiii,  1904. 


368  THE    ORAL    TISSUES 

of  rapidly  growing  epithelioma  it  is  seen  that  in  the  early  stages  of 
the  proliferation  of  the  Malpighian  layer,  the  cells  of  the  invading 
tissue  at  first  pass  through  a  cycle  of  somatic  divisions,  exactly  as  in 
the  early  stage  of  reproduction  tissue.  The  resemblance  may  extend 
to  the  frequent  production  of  giant  cells,  a  common  occurrence  in 
each  case.  As  cell  multiplication  proceeds,  however,  a  change  passes 
over  the  cells  themselves.  The  protoplasmic  continuity,  to  which 
the  "prickly"  character  is  due,  becomes  more  or  less  obliterated, 
and  the  cells  assume  that  appearance  of  indifferent  germ  tissue  so 
well  known  as  a  feature  of  the  elements  of  which  malignant  growths 
are  largely  made  up." 

The  conclusions  to  which  these  observers  came  were  that  malig- 
nant new-growths  are  really  nothing  more  nor  less  than  "reproduc- 
tive (gametogenic)  tissue  arising  in  abnormal  situations  and  pos- 
sessed of  an  independence  and  power  of  growth  like  that  of  the  testis 
in  the  mammalian  body". 

The  occurrence  of  the  phenomena  described  by  them  was  cor- 
roborated, in  the  case  of  the  lower  vertebrates,  by  Bashford  and 
Murray,  in  January,  1904. 

To  sum  up.  It  may  be  said  that  if  an  explanation  were  insisted 
upon  for  the  causation  of  this  disease,  the  opinions  held  by  Calcott 
Fox  and  MacLeod  in  "A  Case  of  Paget's  Disease  of  the  Umbilicus," 
appearing  in  the  British  Journal  of  Dermatology,  vol.  xvi,  No.  2, 1904, 
taken  in  conjunction  with  the  so-called  "autotoxic  hypothesis," 
might  in  all  probability  throw  some  light  on  the  subject. 

The  former  writers  remark,  "It  has  never  been  demonstrated, 
and  it  seems  highly  improbable,  that  the  degenerated  cells  which 
occur  in  the  epidermis  or  the  epithelium  in  Paget's  disease  can  take 
on  malignant  characters.  It  appears  to  us,  however,  more  reason- 
able to  assume  that  the  malignant  growth  originates  in  epithelial  or 
epidermal  cells  which,  not  having  degenerated,  have  reverted  and 
assumed  a  capacity  for  proliferation  through  the  prolonged  action  of 
some  cause  which,  acting  most  powerfully  on  undifferentiated  cells, 
produces  their  degeneration,  than  in  a  matrix  of  cells  which  has 
been  deposited  there  at  some  period  more  or  less  remote."  The 
latter  assume  that  "The  products  of  perverted  metabolism  in  animal 
organs  or  tissues  produce  morbid  effects  in  the  individual's  body." 

In  the  present  instance  it  is  conceivable  that  the  mechanical  and 
physiological  growth  of  the  fibroma  beneath  and  internal  to  its 
epidermal  convering  may  have  induced,  in  the  course  of  time,  the 
perverted  metabolism  above  mentioned.     Although  the  growth  of 


DISEASES    OF    THE    ORAL    MUCOUS    MEMBRANE  369 

the  neoplasm  was  slow,  it  is  entirely  probable  that  it  was  only  quite 
recently  that  the  epithehum  had  undergone  the  carcinomatous 
changes. 

Sir  James  Paget/  who  first  drew  attention  in  the  St.  Bartholo- 
mew's Hospital  reports  for  1874  to  cases  of  a  certain  disease  of  the 
mammary  areolae,  has  been  followed  by  many  other  contributors  to 
a  general  knowledge  of  the  subject,  among  whom  may  be  mentioned 
Butlin,"-  Wickham,*^  Darier,*  Duhring,=*  Wile,^  etc.  It  has,  how- 
ever, only  recently  been  found  that  the  genitaha  may,  at  time's, 
undergo  similar  morbid  changes,  histories  having  been  put  on 
record  by  Pick,  Rolleston,^  Dubreuilh,^  Ravogh,^  and  others, 
including  Fordyce,  in  1903,  at  the  New  York  Dermatological  Society; 
while  Calcott  Fox  and  Macleod  {loc.cit.)  have  reported  one  instance  of 
Paget's  disease  of  the  umbilicus. 

The  definition  of  "mahgnant  papillary  dermatitis"  has  been 
applied  to  this  affection;  and  it  constitutes,  in  the  words  of  MacLeod 
("A  Practical  Handbook  of  the  Pathology  of  the  Skin,"  1903), 
"a  peculiar  type  of  persistent  dermatitis  which  clinically  in  its  early 
stages  somewhat  resembles  chronic  eczema.  .  .  .  .  In  later  stages  of 
the  disease  its  mahgnant  character  becomes  evident,  and  a  carcinoma 
develops." 

CONCLUSIONS 

The  signification  and  direct  bearing  on  practical  dental  and  oral 
surgery  of  mahgnant  disease  of  the  gums  is  immediately  important 
and  clear.  That  certain  of  the  innocent  neoplasms  of  the  fully 
formed  connective  tissue  type  may  undergo  secondary  malignant 
changes  is  a  well-known  fact  in  pathology.  Thus,  lipomata  may 
become  sarcomatous,  and  papillomata  and  verrucae  carcinomatous. 
Fibromata  usually  are  subject,  if  they  degenerate  or  become  altered 
in  structure,  to  calcification  and  mucoid  softening,  or  ulceration 

1  ''Disease  of  the  Mammary  Areola  Preceding  Cancer  of  the  Mammary 
Gland."     St.  Bartholomew's  Hospital  reports,  1874. 

2  Medico-Chirurgical  Transactions,  1876. 
^American  Journal  of  the  Medical  Sciences,  1883. 
"•  Complcs  rendus,  Sociele  de  Biologic,  1889. 
^American  Journal  of  the  Medical  Sciences,  1884. 

"  International  Congress  of  Dermatology,  Paris,  1889. 
'^Pathological  Society  Transactions,  1897. 
*  International  Medical  Congress,  Rome,  1894. 
'■'British  Journal  oj  Dermatology,  1901. 
24 


37©  THE    ORAL   TISSUES 

when  placed  on  exposed  surfaces.  It  was,  probably,  a  mere  accident 
in  the  present  instance  that  a  fibroma  should  bear  on  its  periphery- 
signs  of  malignancy.  Epithelia,  especially  of  the  pavement  or 
squamous  type,  are  particularly  prone  to  prohferate,  and  it  is  a 
matter  of  great  surprise  that  the  oral  epithelium  does  not  oftener 
produce  carcinomata. 

The  epithelium  of  the  mucous  membrane  of  the  cheek  would 
almost  seem  to  possess  a  large  measure  of  immunity  from  it.  Here 
there  is  apparently  a  frequent  source  of  irritation  and  tissue  change; 
and  yet  cheek  carcinomata  are  most  uncommon.  The  surface  of  lip, 
tongue,  and  palate  are,  however,  favourite  sites. 

The  extreme  rarity  of  malignant  disease  of  the  gums  must  not  be 
taken  too  literally;  it  may  be  commoner  than  is  supposed,  for  it  is 
impossible  to  say  how  many  fibromata  have  been  excised  which 
were  already  undergoing  these  degenerations  but  which  remained  un- 
recognised inasmuch  as  no  microscopical  examination  had  been  made. 

From  the  point  of  view  of  the  frequency  of  its  occurrence  it  might, 
perhaps,  occupy  a  position  intermediate  between  that  of  the  cheeks 
and  the  other  structures  named.  As  the  removal  of  a  diseased 
periodontal  membrane  will  often  obviate  the  formation  and  develop- 
ment of  a  dental  cyst,  or  even  perhaps  sarcoma  or  epithelioma  of  the 
jaws,  so  too  the  removal  of  what  is  considered  to  be  merely  an 
"ordinary  epulis"  may  prevent  the  onset  of  Paget's  disease.  Extir- 
pation may  really  signify  prevention  of  its  inception. 


CHAPTER  XV 

ODONTOMES  AND  ODONTOCELES 

Microscopical  Elements  in: — (i)  Epithelial  odontomes;  (ii)  Follicular 
odontomes;  (iii)  Radicular  and  (iv)  Composite  odontomes;  (v)  Sub- 
capsular odontoceles;  (vi)  Extra-capsular  odontoceles. 

Definition. — "A  tumour  composed  of  dental  tissues  in  varying 
proportion  and  different  degrees  of  development  arising  from  tooth 
germs  or  teeth  still  in  the  process  of  growth" — (Sir  John  Bland- 
Sutton).  "An  odontome  is  a  tumour  derived  from  the  special  cells 
concerned  in  tooth  development It  is  a  mass  of  new  forma- 
tion which  tends  to  grow  or  persist,  fulfils  no  physiological  function, 
and  has  no  typical  termination;  it  also  fulfils  Thoma's  definition  of  a 
tumour  being  'an  autonomous  or  independent  new  growth/  the 
law  laid  down  by  him  that  'it  reproduces  with  more  or  less  deviation 
the  structure  of  the  part  from  which  it  primarily  arises.'"  ("The 
Report  on  Odontomes,"  London,  1914.) 

Classification. — According  to  Sir  John  Bland-Sutton,^  these 
tumours  may  be  grouped  as  follows: — 

(A)  Aberrations  of  the  enamel  organ: — 

1.  Epithelial  odontomes. 

2.  Calcified  epithelial  odontomes. 

(B)  Aberrations  of  the  follicle  (capsule) : — 

1.  Follicular  cysts.  , 

2.  Fibrous  odontomes. 

3.  Cementomes. 

(C)  Aberrations  of  the  dental  papilla: — 
I.  Radicular  odontomes. 

(i)  Dentomata. 
(ii)  Osteo-dentomata. 
(iii)  Cementomes. 

(D)  Aberrations  of  the  whole  tooth  germ: — 
Composite  odontomes. 

(E)  Anomalous    odontomes.     (Compound    follicular    odon- 
tomes.) 

1  Trans.  Odonto.  Soc,  Nov.  1887. 
371 


372  THE    ORAL    TISSUES 

This  classification  has  been  revised  (1914)  by  a  committee  com- 
posed of  Messrs.  Douglas  Gabell,  W.  Warwick  James,  and  J.  Lewin 
Payne,  and  is  as  follows: — 

1.  Epithelial  odontomes  (where  the  abnormal  development 
occurs  in  the  dental  epithelium  only): — - 

1.  Multilocular  cysts. 

2.  Dentigerous  cysts. 

3.  Dental  cysts. 

2.  Composite  odontomes  (where  the  abnormal  development  takes 
place  primarily  in  the  dental  epithelium,  and  secondarily  in  the 
dental  papilla,  and  may  occur  in  the  foUicle   (capsule)  also): — 

1.  Complex  composite  odontome. 

2.  Compound  composite  odontomes. 

3.  Geminated  composite  odontomes. 

4.  Gestant  composite  odontomes,  in  which  a  denticle 
is  contained  within,  or  surrounded  by,  the  walls  of  a 
tooth,  called  by  Arkovy  "  odontoma  internum  liberum. " 

5.  Enamel  nodules. 

6.  Dilated  composite  odontomes. 

3.  Connective-tissue  odontomes  (where  the  abnormal  develop- 
ment takes  place  in  the  dental  tissues  of  mesodermic  origin  alone) : — 

1.  Fibrous  odontomes. 

2.  Cementomes. 

Epithelial  Odontomes 

Origin. — They  may  arise  from  abnormal  growth  of  the  epithelial 
"rests"  found  in  (i)  diverticula  from  enamel  organs,  or  (ii)  aborted 
tooth  germs. 

Synonym. — "Multilocular  cystic  tumours." — (Eve). 

Macroscopical  Appearances. — A  soft  mass  containing  cysts  of 
various  sizes  lying  between  the  external  and  internal  alveolar 
plates  which  have  become  much  attenuated  and  enlarged  (Figs. 
331  and  332).  A  more  or  less  completely  formed  tooth  can  generally 
be  found  in  the  neighbourhood  of  the  growth.  At  times  portions 
of  the  tumour  may  become  ossified,  columns  of  bony-like  substance 
being  embedded  in  its  midst;  or  the  whole  growth  may  undergo 
osseous  changes.  Such  cases  have  been  described  by  Tomes  and 
Miller. 


ODONTOMES  AND  ODONTOCELES 


373 


Fig.  331.  Fig 

Fig.  331. — Lateral  view  of  an  epithelial  odontome 
Fig.  332. 


332. 

Actual  size. 
A  superficial  aspect  of  the  same , sh owing  several  cysts. 


Fig.  333.— A  section  through  the  thickest  portion  of  the  mass,  showing  the 
epithelial  columns  extending  into  the  mesodermic  tissue.  Prepared  by  hardening 
in  alcohol.  Stained  with  h£ematoxylene.  Magnified  45  times.  E.  Epithelium; 
c.   Connective  tissue. 


374 


THE    ORAL   TISSUES 


HISTOLOGY 


The  mass  chiefly  comprises  bundles  of  connective  tissue  fibres, 
densely  and  closely  packed;  in  places  a  round  celled  infiltration, 
which  probably  represents  embryonic  mesodermic  tissue,  can  be 
observed. 


Fig.   334. — Similar   to  the  preceding.     Magnified  50  times.      C.  Early  stages  in 
the  formation  of  a  cyst;  E,  Epithelium. 


Greater  interest,  however,  centres  in  the  epitheHum.  This 
extends  primarily  in  the  form  of  solid  rods  or  territories  into  the 
substance  of  the  odontome.  The  epitheKal  columns  anastomose 
and  branch  freely.  In  some  situations  they  are  extremely  narrow, 
in  others  broad.     Thus  they  vary  in  width  from  0.6  mm,  to  i.o  mm. 


ODONTOMES  AND  ODONTOCELES 


375 


Fig.  335. — Similar  to  the  preceding.  A  longitudinal  section  through  the 
entire  wall  of  a  small  cyst,  showing  its  contents,  e.  Epithelial  tissue;  C.  Cyst 
contents;  m.   Mesodermic  tissue. 


Fig.  336. — A  portion  of  the  wall  of  a  cyst  in  an  epithelial  odontoma.  Pre- 
pared as  the  preceding.  E.  Epithelial  cells;  D.  Degenerate  cells;  c.  Colloid  mate- 
rial which  constitutes  the  cyst  contents. 


376  THE    ORAL    TISSUES 

Islands  of  mesodermic  fibrous  tissue  are  often  formed  by  the  junction 
of  the  under  side  of  the  epithehal  involutions. 

The  cells  here  are  very  similar  in  constitution  to  those  of  the 
deepest  layers  of  the  oral  epithelium.  In  shape  they  vary  somewhat. 
Those  at  the  margins  of  the  ingrowths  are  small  and  closely  packed 
together,  each  having  nuclei,  with  pronounced  chromatin  granules 
and  karyoplasm.  They  are  cubical  in  shape.  Those  in  the  central 
portions  of  the  mass  are  branched,  and  have  elongated  flattened 
nuclei,  many  of  which  contain  nucleoli  in  addition  to  the  karyoplasm. 
Many  signs  of  rapid  subdivision  of  the  cells  can  be  noted.  In  the 
centre  of  the  earliest-formed  islands  the  method  of  breaking  down 
or  dissolution  of  the  cells,  with  the  first  commencement  of  cystic 
degeneration,  can  be  easily  studied.  They  assume  a  shrunken 
appearance,  with  hydropic  nuclei.  Joined  by  their  processes,  they 
bear  a  distant  resemblance,  as  Bland-Sutton  has  suggested,  to  the 
stellate  cells  of  the  enamel  organ. 

Follicular  Odontomes  or  Dentigerous  Cysts 

Origin. — An  excessive  amount  of  secretion  of  fluid  between  the 
enamel  or  Nasmyth's  membrane  and  the  dental  capsule,  which, 
accumulating,  distends  the  space  and  produces  a  cyst. 

Synonym. — Dentigerous  cyst. 

Contents. — A  glairy  fluid,  with  crystals  of  cholesterine  and  broken 
down  epithelial  cells  in  suspension,  and  a  fully  or  partially  developed 
tooth  or  teeth  lying  in  its  interior. 

They  may  be  (i)  Simple  (containing  one  tooth)  or  (ii)  Compound 
(containing  many  teeth). 

GENERAL    CONSIDERATIONS 

Teeth  found  in  these  cysts  usually  possess  no  Nasmyth's  mem- 
brane. The  recognition  of  any  new  fact  is  likely  to  be  succeeded 
by  the  advancement  of  some  novel  theory  which  may  serve  a  useful 
end  in  attempting  to  explain  what  is  otherwise  inexplicable.  Such 
is  the  difficulty  of  obtaining  reliable,  and  therefore,  scientific  infor- 
mation on  many  obscure  physiological  and  pathological  processes, 
that  occasionally  the  most  commonplace  and  minor  observation 
becomes  the  progenitor  of  a  vast  store  of  valuable  knowledge. 

These  generalisations  apply  equally  to  the  various  regions  of  the 
body,  and  to  every  organ  or  tissue  which  they  contain  or  of  which 


ODONTOMES  AND  ODONTOCELES  377 

they  are  constructed.  If  etiological  or  pathological  processes  were 
more  frequently  contemplated  from  the  anatomical  standpoint,  there 
would  be  less  confusion  as  to  the  manner  of  operation  of  morbid 
changes,  and  as  to  the  successful  and  non-empirical  treatment  of 
diseased  conditions. 

It  would  seem  at  first  sight  a  somewhat  trivial  and  unimportant 
matter  that  the  retained  teeth  of  dentigerous  cysts  may  have  no 
Nasmyth's  membrane  investing  their  coronal  surfaces,  or,  indeed, 
any  portion  of  them.  But  it  is  probably  true.  Some  time  ago 
the  author  removed  from  a  dentigerous  cyst  a  tooth  so  affected. 

In  the  mouth  of  a  patient,  a  boy  of  nine  and  a  half  years,  there 
existed  a  swelling  in  the  neighbourhood  of  the  left  mandibular 
second  deciduous  molar.  After  operation,  the  second  premolar 
was  easily  detached  uninjured  from  the  floor  of  the  cavity  on  which 
it  was  lying  horizontally.  It  was  thereupon  subjected  to  Paul's 
phloroglucin  and  nitric  acid  mixture,  in  order  to  ascertain  if  the 
enamel  cuticle  was  intact  or  diseased.  It  was  found  to  be  entirely 
absent. 

The  rarity  of  this  form  of  cyst,  or  follicular  odontome,  according 
to  Bland-Sutton,  and  the  heretofore  incorrect  statements  as  to  the 
nature  of  the  membrane,  have  prevented  much,  if  any,  investigation 
of  the  subject.  Although  at  present  the  author  has  been  fortunate 
enough  to  obtain  one  specimen  only,  it  is,  however,  extremely  prob- 
able that  it  is  the  rule,  that  when  dentigerous  cysts  occur  there 
is  concomitant  absence  or  failure  of  development  of  Nasmyth's 
membrane. 

To  what  theories  does  this  fact,  then,  give  rise? 

The  anatomical  relationships  of  the  parts  around  an  unerupted 
tooth  must  be  briefly  recalled.  Beginning  from  within,  and  passing 
outwards,  the  following  structures  meet  the  eye,  and  are  placed  in 
order,  as — the  external  free  surface  of  the  enamel,  the  translucent 
pelhcle  of  Nasmyth's  membrane,  its  cellular  layer,  the  internal 
layer  of  the  dental  capsule,  and  the  external  layer  of  the  same. 

The  cyst  wall  consists  of  "dense  strands  of  longitudinally  arranged 
connective-tissue  fibres,  which  are  thick  and  strong,  but  loose  in 
texture  nearest  the  bone;  while  gathered  into  bundles  further  in, 
composing  the  bulk  of  the  cyst,  are  connective  tissue  fibres  and  cells, 

all   freely  supplied  with  blood-vessels Ultimately  a  fully 

developed  dentigerous  cyst  is  lined  with  a  layer  of  epithelial  cells, 
one  or  more  deep."  Like  all  cysts  of  new  formation.  Whence 
comes  this  layer  of  epithelium?     It  is  probably  identical  with  the 


378  THE    ORAL   TISSUES 

external  epithelium  of  the  enamel  organ,  which,  on  completion  of 
development,  becomes  the  cellular  layer  of  Nasmyth's  membrane. 
If  this  is  the  case,  then  the  cyst  contents  are  probably  formed  by  the 
degeneration  and  liquefaction  of  the  stellate  reticulum. 

Inspection  of  a  tooth  germ  at  an  early  stage  of  growth,  when  cut 
in  a  vertical  position,  reveals  the  stellate  reticulum  of  the  enamel 
organ  bounded  externally  by  a  layer  of  small  round  cells  (external 
epithelium),  internally  by  round  or  polygonal  cells  (^stratum  inter- 
medium), and  cylindrical  cells  with  prominent  nuclei  (internal 
epithelium  or  ameloblasts).  The  first-named,  at  one  time,  extends 
without  interruption  almost  around  the  entire  tooth  germ.  The 
actual  date  of  its  disappearance  is  unknown.  It  is  clear,  however, 
that  that  portion  situated  near  the  cusps  or  incisive  edges  of  the 
teeth  is  the  last  to  atrophy. 

Of  all  the  structures  in  the  enamel  organ  which  could  possibly 
originate  the  thick,  glairy  fluid  which  forms  the  contents  of  the 
cyst,  the  stellate  reticulum  is  the  one.  As  has  been  already  mentioned 
the  external  epithelium  probably  remains  as  the  internal  lining  of 
epithelial  cells  in  the  fully  developed  cyst  wall.  It  has,  in  this 
instance,  been  modified  as  far  as  its  functions  have  been  concerned, 
and  has  never  formed  the  cellular  layer  of  the  enamel  cuticle,  for 
that  thin  film  has  never  existed.  It  is  impossible  to  conceive  that, 
had  it  been  present,  it  had  been  destroyed  by  any  pressure  or 
chemical  action  on  the  part  of  the  cyst  contents. 

The  internal  epithelium  cannot  presumably  take  part  in  the 
degeneration.  For  its  work  is  accomplished  in  the  formation  of  the 
enamel,  finally,  in  an  atrophied  or  exhausted  state,  losing  its  cellular 
identity,  and  degenerating  into  the  keratinous  homogeneous  pel- 
licular layer  of  the  membrane. 

There  remains,  therefore,  the  stratum  intermedium  and  the  stellate 
cells.  Of  the  former  little  is  known  concerning  either  its  function 
or  its  real  anatomical  relationships.  The  author  ventures,  therefore, 
logically  and  reasonably  to  believe  that  it  is  the  cells  of  the  "packing 
material"  which  are  the  all-important  factor. 

One  argument  against  the  acceptance  of  this  view  which  might 
undoubtedly  be  raised  is  that  the  stellate  reticulum  disappears  very 
early  in  the  development  of  the  tooth.  This  is  true.  But  there 
can  be  no  objection  to  the  expression  of  the  opinion  that  a  portion 
of  it  may  escape  atrophy,  and,  remaining  behind  as  an  unabsorbed 
body,  have  its  constituent  cells  suddenly  undergoing  centrifugal 
proliferation,  with  its  inevitable  termination  of  degeneration,  death, 


ODONTOMES    AND    ODONTOCELES  379 

and  liquefaction.  The  fluid  thus  produced  would  have  no  difficulty 
in  surrounding  the  whole  surface  of  the  crown,  and,  if  the  roots 
were  completed,  enveloping  the  entire  or  greater  part  of  the  tooth. 

Still  it  is  not  easy  to  prove  the  anatomical  origin  of  a  dentigerous 
cyst  in  the  light  of  present  knowledge.  Nevertheless,  one  or  two 
considerations  may  be  applied  to  its  study.     Thus: — 

(a)  There  is  an  analogy  in  the  formation  of  epithelial  odontomes, 
which  are  believed  to  arise  from  irregular  diverticula  from  or  un- 
atrophied  remnants  of  the  tooth  band. 

(b)  There  is  a  further  similarity  between  the  microscopical 
appearances  of  the  cells  of  an  epithelial  odontome  which  are  about  to 
break  down  and  the  cells  of  the  stellate  reticulum  as  Sir  John  Bland- 
Sutton^  has  already  noticed  ("Tumours  Innocent  and  Malignant," 
4th  edition,  1906),  especially  when  they  are  becoming  aged. 

(c)  The  teeth  found  in  follicular  odontomes  are  often  only  par- 
tially complete.  This  agrees  with  the  fact  that  the  stellate  reticulum 
disappears  early  in  the  life-histories  of  teeth. 

{d)  And,  lastly,  by  a  process  of  elimination  it  is  satisfactory 
to  surmise  that  no  other  constituent  of  the  enamel  organ  could 
produce  tTie  cyst  contents  than  these  cells. 

These  remarks  are  based  on  the  assumption  that  some  cells  of 
the  enamel  organ  play  an  important  part  in  the  genesis  of  a  dentig- 
erous cyst.  There  is  just,  however,  one  other  possibility  if  this 
suggestion  is  incorrect,  and  that  is  that  the  follicle  itself  may  originate 
its  own  cyst. 

Sections  of  the  dental  capsule,  when  made  at  the  time  of  its  fullest 
growth,  exhibit  many  winding  tube-like  bodies  composed  of  epithe- 
lium, which  run  in  an  inward  direction,  and  are  almost  exclusively 
confined  to  its  inner  border,  i.e.,  the  part  which  is  contiguous  with 
and  closely  applied  to,  Nasmyth's  membrane. 

Now,  it  is  possible,  but  unlikely,  that  proliferation  and  growth 
occur  in  one  or  more  of  these  bodies.  As  these  are  placed  externally 
to  the  external  epithelium  of  the  enamel  organ,  one  would  expect 
to  find  the  enamel  cuticle  intact  on  the  surface  of  the  tooth  embedded 
in  the  cyst.     But  this  is  not  so. 

Hence  it  is  that,  taking  all  things  into  consideration,  and  weighing 
carefully  the  pros  and  cons,  the  author  ventures  to  express  his  belief 
in  the  origin  of  the  cyst  in  the  manner  already  detailed, — a  belief 
confirmed  by  the  fact  that  Messrs.  W.  A.  Maggs  and  Pare  also 

i"The  central  cells  degenerate  and  give  rise  to  tissue  resembling  the  stellate 
reticulum  of  the  enamel  organ" — p.  228. 


38o 


THE    ORAL    TISSUES 


Fig.  337. — The  mucous  membrane  and  soft  tissue  external  to  the  wall  of  a 
follicular  odontome.  Prepared  by  hardening  in  alcohol.  Stained  with  Ehrlich's 
acid  hEematoxylene.  Magnified  230  times.  Oe.  Oral  epithelium;  G.  Tissues  of 
the  gum;  p.   Periosteum;  b.   Attenuated  bone. 


Fig.  338. — The  wall  of  a  follicular  odontome.  The  innermost  part  of  the 
section  in  Fig.  337.  B.  Attenuated  bone;  w.  Wall  of  cyst;  bv.  Blood-vessels; 
F.  Internal  surface  of  wall. 


ODONTOMES  AND  ODONTOCELES  381 

noticed  the  absence  of  Nasmyth's  membrane  under  similar  condi- 
tions, and  noted  the  anomaly  in  Guy's  Hospital  Gazette  for  1904.  ■ 

Follicular  odontomes  are  undoubtedly  congenital  or  develop- 
mental in  their  origin.  But  a  good  deal  of  confusion  still  exists 
as  to  their  pathogenesis.  It  is  unnecessary  to  enter  into  the  argu- 
ments of  many  writers.  Let  it  therefore  suffice  to  recall  that, 
among  the  older  ones,  Broca  believed  that  they  arose  within  the 
tooth  capsule,  sac,  or  follicle,  the  enamel  organ  having  disappeared 
"under  morbid  influences;"  that  Malassez  explained  that  they 
were  due  to  hypertrophy  of  epithelial  rudiments  of  the  enamel 
organ;  that  Albarran  considered  they  were  inaugurated  by  the 
proliferation  of  the  aborted  epithehum  of  the  fibrous  tissues  normally 
present  in  the  iter  dentis;  and  that  Salter  ascribed  to  "a  sort  of 
epithehum"  clothing  the  so-called  enamel  pulp  "the  power  of 
assuming  the  function  of  secreting  fluid." 

Bland-Sutton  defines  them  thus:  "Swellings  [which  are]  often 
called  dentigerous  cysts,  a  term  which  has  come  to  be  used  so  very 
loosely  that  it  should  be  discarded  in  the  necessity  for  precision. 
They  arise  commonly  in  connection  with  teeth  of  the  permanent  set, 
and  especially  with  the  molars;  sometimes  they  attain  large  dimen- 
sions and  produce  great  deformity,  especially  when  they  arise  in  the 
upper  jaws  and  happen  to  be  bilateral.  Rarely  they  occur  in 
connection   with   supernumerary   teeth.     The   wall   represents   an 

expanded  tooth-capsule The  cavity  of   the  cyst  usually 

contains  viscid  fluid  and  the  crown  or  the  root  of  an  imperfectly 
developed  tooth.  Occasionally  the  tooth  is  loose  in  the  capsule, 
sometimes  inverted,  and  often  its  root  is  truncated;  exceptionally 
the  tooth  is  absent  or  represented  by  an  ill-shaped  denticle.  The 
walls  of  the  cyst  always  contain  calcific  or  osseous  matter;  the 
amount  varies  considerably." 

Tomes  and  Nowell  write:  "The  follicular  cyst  arises  in  con- 
nection with  teeth  retained  in  the  jaws,  generally  premolars  or 
molars.  They  cause  great  distension  of  the  jaws"  (p.  725);  and, 
in  accounting  for  their  mode  of  formation  and  generation  of  the 
fluid  contents,  assert  (p.  732):  "When  the  development  of  the 
enamel  is  completed,  its  outer  surface  becomes  perfectly  detached 
from  the  investing  soft  tissue,  and  a  small  amount  of  transparent 
fluid  nf)L  uncommonly  collects  in  the  interval  so  formed." 

It  is  a  well-known  fact  that  the  deciduous  and  permanent  teeth, 
when  about  to  erupt,  may  present  over  their  crowns  a  bluish,  soft 
vesicle  containing  serum  (eruption  cysts).     It  is  not  an  easy  matter 


382  THE    ORAL    TISSUES 

to  explain  the  presence  of  the  vesicles  over  the  teeth  of  succession 
becatise  of  the  presence  of  the  absorbent  organ,  and  nearly  always 
follicular  odontomes  are  formed  in  connection  with  the  members 
of  the  permanent  series.  The  authors  just  cited  believe  that  this 
iact — viz.  the  occurrence  of  vesicles — furnishes  an  explanation  of 
the  manner  in  which  cystic  tumours  containing  unerupted  teeth 
arise.  "Fluid  collects  between  the  enamel  and  the  tooth  capsule," 
they  say.  Assuming  this  statement  to  be  correct,  and  although 
no  mention  is  made  of  the  enamel  cuticle,  one  is  led  to  ask  "Whence 
comes  the  fluid?  Why  does  it  collect?"  And  one  is  told  that 
fluid  is  normally  and  universally  present  over  the  crowns  of  un- 
erupted teeth.  If  this  were  so,  one  would  expect  to  find  that 
follicular  odontomes  were  extremely  common,  which  they  are  not, 
and  that  unerupted  teeth  could  never  remain  in  an  innocuous  state 
in  the  bones  of  the  jaws,  which  they  do. 

Paul,  writing  in  1894,  observed:  "On  dissecting  them  {i.e.,  the 
teeth  of  sheep  and  monkey  in  their  sacs),  it  appears  that  at  a  certain 
stage  the  crown  of  the  tooth  was  quite  free  inside  the  sac,  but  that  at 
a  slightly  later  stage  the  sac  adhered  to  the  tooth,  although  it  could 
be  easily  stripped  from  it." 

The  above  named  authors  proceed:  "As  the  cyst  enlarges,  the 
contiguous  bone  is  removed  to  make  room  for  it,  fresh  bone  being 
concurrently  deposited  on  the  outside  of  the  jaw.  In  the  case  of  such 
cyst  lying  in  front  of  a  tooth  which  is  being  cut,  it  is  obliterated  by 
the  advancing  tooth  or  it  bursts;  but  when  situated  deeply  in  the 
jaw,  a  cystic  tumour  may  be  the  result." 

Finally,  Heath  defines  follicular  odontomes  as  "cysts  [which] 
contain  one  or  more  teeth  in  their  interior  or  in  their  wall.  The 
teeth  may  be  well  formed  or  may  be  quite  rudimentary,  consisting 
of  irregular  masses  of  bone  and  enamel." 

The  Origin  of  the  Cystic  Fluid 

Already  the  opinion  has  been  expressed  that  the  fluid  contents 
of  these  tooth-bearing  cysts  is  derived  from  the  degenerated  cells 
of  the  stellate  reticulum  of  the  enamel  organ.  Instead  of  becoming 
absorbed  in  the  usual  way,  they  may,  for  some  recondite  reason, 
not  disappear,  but  may  further  degenerate  and  liquefy,  and  produce 
a  potential  cavity  which,  on  being  filled  with  fluid,  is  the  beginning 
of  the  formation  of  the  cyst. 


ODONTOMES    AND    ODONTOCELES  383 

General  Observations 

As  bearing  on  the  pathology  of  these  cases,  it  is  necessary  to  recall 
as  succinctly  as  possible  the  anatomical  topography  of  the  parts, 
and  to  explain  the  grounds  for  the  belief  that  the  liquefaction  of  the 
stellate  reticulum  would  account  for  the  fluid  in  a  dentigerous  cyst. 
The  enamel  organ  at  maturity  consists  of  four  different  cell  elements, 
arranged  from  within  outwards,  as  the  (i)  internal  epithelium  or  the 
ameloblasts—  elongated,  columnar  cells,  measuring  15/x  to  20/x,  set 
in  immediate  apposition;   (2)   the  stratum  intermedium,  a  narrow 
layer  of  small  polygonal  cells;  (3)  the  stellate  reticulum,  mucoid  cells 
with  round  nuclei  and  numerous  long  branching  processes;  and  (4) 
the  external  epithelium,  a  layer  of  single  rounded  or  flattened  cells. 
The  functions  of  these  are  supposed  to  be  as  follow:     The  first  to 
form  enamel,  and,  when  "spent,"  the  translucent  pellicle,  or  inner 
layer  of  Nasmyth's  membrane;  the  second  to  recruit  or  rehabilitate 
the  ameloblasts;  the  third  to  act  as  a  "packing"  material  to  the 
enamel  organ;  and  the  last  (somewhat  doubtful,  but  believed  by 
some — Professor  Paul,  for  instance)   eventually  to  constitute,  on 
persistence,  the  cellular  layer  of  the  enamel  cuticle.     Now,  outside 
this  external  epithelium,  which,  it  is  important  to  note,  is  in  direct 
continuity  with  the  fibrous  tissues  which  form  the  dental  capsule- 
there  is  no  sharp  Hne  of  demarcation  between  the  two,  though  in 
speaking  of  the  two  structures  one  unconsciously  dissociates  them — 
comes  the  capsule  or  tooth-sac  itself.     Composed,  when  young,  of 
fibrous  tissue  with  a  feeble  supply  of  round  cells,  it  contains  numerous 
gland-like  epithelial  bodies. 

It  is  therefore  clear  that  the  dental  capsule  usually  has,  on  its 
internal  aspect,  a  layer  of  epithelium — viz.,  the  external  epithelium 
of  the  enamel  organ.  It  is  possible,  in  fortunate  circumstances,  to 
show  the  lining  of  the  capsule.  To  give  a  concrete  example:  If 
an  unerupted  first  premolar  be  removed  at  the  age  of  7  to  73^-2,  and 
its  soft-tissued  investment  allowed  to  remain  in  statu  quo  ante,  on 
making  vertical  sections  one  can  see,  under  the  4  mm.  objective,  the 
ameloblasts  becoming  converted  into  the  translucent  pellicle  of  Nas- 
myth's membrane.  At  the  cervical  margin  of  such  a  tooth  they  are 
elongated  and  cylindrical,  but  little  altered  from  those  of  activity — 
merely  shorter.  Higher  up,  nearer  the  cusps  of  the  crown,  however, 
they  are  shrunken  and  flattened,  and  while  still  retaining  their 
prominent  nuclei,  often  become  hexagonal  or  pentagonal  in  outline. 
In  the  neighbourhood  of  the  extremities  of  the  cusps  they  have 


384  THE    ORAL    TISSUES 

become  fused  to  form  a  homogeneous  membrane — the  pellicular  or 
inner  layer  of  Nasmyth's  membrane.  Next  to  them  is  a  single 
fiat  layer  of  cells,  the  external  epithelium  closely  applied  to  their 
surface.  Though  so  intimately  approximated  there  is  a  wide  range 
of  difference  from  an  embryological  point  of  view  between  the  two, 
the  external  epithelial  cells  being  ectodermic  and  the  dental  capsule 
mesodermic  in  origin. 

Now,  if  the  stellate  cells  of  the  enamel  organ  undergo  further 
softening,  disintegration  and  liquefaction,  the  first  stage  of  the  forma- 
tion of  a  follicular  odontome  is  inaugurated.  Little  by  little  the 
fluid  collects,  until  a  cyst  is  produced,  with  the  external  epithelial 
cells  on  the  outside  and  the  internal  epithelial  cells  on  the  inside. 
The  first  form  a  definite  layer  of  epithelial  cells  and  are  not 
secretory  cells.  The  second  has  sometimes  not  had  an  opportunity 
of  becoming  metamorphosed  into  the  pelUcle  of  the  enamel  cuticle 
(this  is  quite  conceivable,  and,  really,  a  common-sense  view)  on 
account  of  the  accumulation  of  the  fluid;  hence  its  absence  on  three 
authenticated  occasions.  At  other  times  the  fluid  has  probably 
collected  after  the  production  of  the  pellicle  had  occurred,  but  the 
cellular  layer,  instead  of  appearing  on  the  surface  as  part  of  Nas- 
myth's membrane,  remained  as  the  adventitious  lining  of  the  cyst 
wall. 

Another  fact  in  agreement  with  the  opinion  which  is  being  pos- 
tulated is  the  striking  anatomical  resemblance  between  the  degenerate 
cells  of  the  stellate  reticulum  and  the  degenerating  cells  of  an  epi- 
thelial odontome.^ 

The  majority  of  the  epithelial  bodies,  derived  from  the  fenestration 
of  the  tooth  band,  may  give  rise  to  the  eruption  cysts  or  epithelial 
odontomes,  supernumerary  teeth,  etc. 

It  is  also  conceivable  that  for  some  reason  or  other  the  cells  of  one 
or  more  of  these  gland-like  bodies  might  undergo  karyokinesis,  and, 
like  the  paradental  "rests,"  though  in  consequence  of  a  dissimilar 
stimulation,  might  rapidly  multiply,  form  large  epithelial  masses, 
of  which  the  central  cells,  cut  off  from  their  nourishment,  would  die, 
degenerate,  and  liquefy.  Here,  then,  a  cyst  might  form — a  capsular 
cyst — but  if  it  were  evolved  from  the  central  portions  of  the  dental 

^  The  phenomena  associated  with  this  degeneration  were  thoroughly  described 
by  Eve  in  an  important  paper  on  "  Cystic  and  Encysted  solid  Tumours  of  the 
Jaws,  with  Observations  on  the  Structure  of  the  Enamel  Organ,"  which  he  read 
before  the  Odontological  Society  of  Great  Britain  in  1885.  From  his  remarks  it 
was  apparent  that  he  had  corroborated  the  results  of  the  researches  of  Falkson 
and  Brj-ck  of  Germany,  who  had  independently  arrived  at  similar  conclusions. 


ODOXTOMES    AND    ODOXTOCELES  385 

follicle,  there  would  ultimately  be  found  two  layers  of  heteromorphic 
cells  in  the  perfected  follicular  odontome  wall;  and  this  is  never  so. 
A  foUicular  odontome  is  therefore  an  example  of  a  congenital 
anomaly. 

HISTOLOGY 

Sections  through  the  entire  wall  of  a  folhcular  odontome  reveal 
most  externally,  an  exceedingly  thin  layer  of  the  mucous  membrane 
of  the  gum,  the  epithelium  of  which  is  not  more  than  a  dozen  cells 
deep.  The  outermost  are  flat,  with  compressed  nuclei;  the  inner 
are  cubical,  as  usual. 

Below  the  oral  epithelium  the  fibrous  tissue  of  the  substance  of 
the  gum  and  the  periosteum  of  the  bone  are  found. 

The  bony  wall  enclosing  the  tumour,  and  expanded  by  its  devel- 
opment, has  necessarily  become  very  attenuated.  The  measure- 
ments of  the  diameters  of  the  bone  and  gum.  tissue  vary  from  o.i 
mm.  and  0.3  mm.  respectively. 

The  cyst  waU  proper,  which  may  have  a  dimension  of  0.5  mm.  in 
width,  lines  the  inner  surface  of  the  bone,  and  consists  of  dense 
strands  of  longitudinally  arranged  connective-tissue  fibres,  which 
are  thick  and  strong,  but  loose  in  texture  nearest  the  bone;  while 
gathered  into  bundles  further  in,  composing  the  bulk  of  the  cyst, 
are  connective-tissue  fibres  and  ceUs,  all  freely  supplied  with  blood- 
vessels. The  former  interlace  in  every  direction,  and  sometimes 
are  so  thickly  placed  together  as  to  present  the  appearance  of 
longitudinally  cut  muscle  fibres.  The  latter,  of  large  size,  run 
in  opposite  directions  to  those  of  the  fibres. 

A  thin  layer  of  epithelial  cells  exists  on  the  most  internal  aspect 
of  the  cyst  wall  forming  its  direct  lining. 

The  central  cehs  cut  off  from  all  nutritive  sources  soon  atrophy, 
die,  and  become  disintegrated,  and  a  cleft  is  formed.  Cystic  fluid 
is  then  produced. 

Ultimately  a  fully  developed  follicular  odontome  is  lined  with 
a  layer  of  epithelal  cells,  one  or  more  deep.  The  contents  stain 
indifferently,  consisting  microscopically  of  an  amorphous  material. 
From  pressure  of  the  accumulating  materials  the  cells  become  flat- 
tened, except  those  on  the  extreme  edge  of  the  cyst. 

Fibrous  odontomata  (endosteal  fibromata)  are  merely  hyper- 
trophies of  the  outer  portion  of  follicular  odontomes;  and  Cementom- 
ata  are  either  an  (i)  ossification  of  fibrous  odontomata,  or(ii)  over- 
growth on  the  part  of  the  osteoblasts  in  the  root  membrane.  Such 
probably  was  the  origin  of  the  cemental  nodule  descrilDed  on  page  80. 
25 


386  THE    ORAL    TISSUES 

Compound  Follicular  Odontomes 

These  are  extremely  rare  in  man;  but  cases  have  been  recorded 
in  the  horse  and  goat.  Sir  John  Bland-Sutton  considers  that  they 
arise  from  the  dental  capsule,  the  osseous  masses  which  are  a  char- 
acteristic feature  being  the  result  of  sporadic  ossification  of  the 
fibrous  tissue  composing  this  structure.  He  found  five  hundred 
denticles  in  the  right  antrum  of  a  girl  aged  11,  and  Ward  Cousins 
{Brit.  Med.  Journ.,  June,  1908)  one  hundred  and  nine  in  the  region 
of  the  second  right  mandibular  molar  in  a  boy  aged  11.  The  latter 
partook  of  the  nature  of  masses  of  hyperplasic  cementum. 

An  interesting  case  has  been  recorded  by  Bland-Sutton.  An 
antral  tumour  of  two  years'  growth,  in  a  patient  aged  11  years,  was 
found  to  contain  soft  vascular  tissue,  inclosing  a  vast  quantity  of 
bony  particles.  More  than  five  hundred  such  pieces  were  counted. 
Microscopical  examination  of  the  particles  showed  their  structure 
to  approximate  that  of  cancellous  bone  identical  with  the  alveolus 
of  the  jaws. 

Radicular   Odontomes 

Origin. — An  aberration  of  the  dentine  germ,  being  therefore  con- 
fined principally  to  the  root  portions  of  teeth. 


Fig.  339.  Fig.  340. 

Fig.   339. — Radicular  odontome;  lingual  aspect.      Actual  size. 
Fig.  340. — Radicular  odontome;  mesial  aspect.     Actual  size. 

Macro  SCO  pical  Appearances. — As  types  of  these  and  composite 
odontomes,  the  two  following  cases  recently  described  by  Dolamore,^ 
may  be  cited. 

Occurring  in  a  patient  of  14  years  of  age,  a  large  "flattened  enamel- 
covered  tooth-like  structure"  was  found  in  the  region  of  the  right 
mandibular  lateral  incisor.  It  had  a  second  conical  mass  fused  to 
its  lingual  surface,  which  ended  below  in  a  smooth  bulbous  tumour 
(see  Figs.  339  and  340).  Its  weight  was  2.7  grammes.  Its  measure- 
ments were  1.2  cm.  in  the  anteroposterior,  1.9  cm.  in  the  vertical, 
and  1.6  cm.  in  the  lateral  diameter.      ■ 

^  Journ.  Brit.  Dent.  Assoc,  1902. 


ODONTOMES    AND    ODONTOCELES 


387 


HISTOLOGY 

It  is  difficult  to  convey  by  means  of  mere  words  or  illustrations 
a  precise  account  of  the  structure  of  the  conglomerate  mass  of  a 
tooth  tumour;  the  reasons  being,  that  the  hard  tissues  are  so  inex- 
tricably confused  and  present  so  many  varied  histological  appear- 
ances which  are  almost  indescribable.  At  the  best  of  times,  there- 
fore, the  patho-histology  can  be  but  feebly  interpreted. 


Fig.  341. — Two  radicular  odontomes. 

Sagittal  sections  having  been  made,  it  was  found  that  the  incisor, 
in  the  case  under  consideration,  is  remarkable  for  the  dense  pigmenta- 
tion of  its  enamel;  the  brown  striae  of  Retzius  are  immature,  while 
the  lines  of  Schreger  are  altogether  wanting.  The  tooth  itself  is 
long.     Immediately  behind  it,  i.e.,  on  its  lingual  aspect,  appears 


Fig.   342. — Radicular  odontome  of  an  incisor  or  maxillary  canine. 

another  smaller  cone-shaped  tooth  with  thick  enamel,  and  a  nar- 
rowed occluded  pulp  chamber.  More  internal  still  is  a  third 
dome-shaped  denticle,  the  enamel  of  which  is  fused  with  that  of  the 
preceding  (Fig.  343  j.  The  dentinal  system  is  absent,  the  centre  of  the 
denticle  being  composed  of  a  large  amount  of  amorphous  or  irregular 
osseous  material.  Following  this,  and  forming  the  remainder  of  the 
ujjjjcr  anrl   inner  surface  of   the  odontome,   arc  several  masses  of 


388 


THE    ORAL    TISSUES 


enamel  intimately  fused,  the  innermost  one  of  all  resembling  a  nar- 
row cone  with  an  arrangement  of  dentinal   tubes.     The  extreme 


Fig.  343- — Sagittal  section  of  a  radicular  odontome.  Prepared  by  grind 
ing.  Unstained.  Magnified  50  times,  e.  Enamel;  d.  Dentine;  o.  Osseous 
tissue. 


fine  point  of  enamel  has  blended  with  the  intervening  mass.     Passing 
still  along  the  periphery  of  the  neoplasm,  and  situated  at  its  inner- 


ODONTOMES    AND    ODONTOCELES 


389 


most  portion,  are  several  radiatory  dentinal  systems,  but  no  cemen- 
tum.  At  its  base  a  slight  amount  of  hyperplasic,  lacunated  cemen- 
tum  is  found.  As  it  passes  up  to  the  labial  surface  once  more,  the 
cementum  is  a  structureless,  narrow  band,  approximating  accurately 
to  the  normal  type. 

The  greater  bulk  of  the  tumour  consists  of  fine-tubed  dentine, 
and  amorphous  osseous  substance  with  occasional  large  cavernous 
spaces.  Deep  down  at  the  base  of  the  second  denticle  are  apparently 
the  remains  of  three  more  irregular,  dwarfed,  rudimentary  outlines 
of  incisor  teeth,  each  having  enormously  thick  coatings  of  deeply 


Fig.  344. — Radicular  odontome.      Magnified  45  times. 
colledion  of  G.  W.  Watson.) 


{From  a  section  in  the 


pigmented  enamel  of  a  low  type,  and  fine-tubed  dentine.  Marked 
lines  of  demarcation  exist  between  these  dentinal  systems  and  the 
bony  deposits.  No  signs  of  absorption  can  be  detected;  but  in 
places  a  few  layers  of  interglobular  spaces,  and  also  enormous  fusi- 
form cavities,  filled  with  debris,  occupy  the  intervening  zone. 

The  odontome  is  instructive  because,  being  a  root  tumour,  there 
is  less  than  the  ordinary  amount  of  cementum.  If  one  may  venture 
to  hazard  an  opinion  as  to  its  genesis  and  further  development,  it 


390 


THE    ORAL    TISSUES 


Fig.   345. — Another  radicular  odontome.      Magnified  45  times.      (Fro7n  a  section 
in  the  collection  of  G.  W.  Watson.) 


Fig.   346. — Another  portion  of  the  preceding.      Same  magnification. 


ODONTOMES    AND    ODONTOCELES  39 1 

would  seem  to  have  been  produced  by  a  fusion  of  several  more  or 
less  complete,  ill-shaped  enamel  organs,  each  of  which  had  attained 
an  unusual  degree  of  physiological  activity,  which  was,  however, 
profoundly  modified  by  certain  pathological  conditions  of  growth. 

The  accompanying  illustrations  show  the  histology  of  two  ra- 
dicular odontomes  in  the  possession  of  G.  W.  Watson,  of  Edinburgh. 
Fig.  344  exhibits  the  dentine  of  the  root  with  a  new  growth,  made 
up  of  ill-formed  (?)  osseous  material,  of  which  the  following  are  the 
chief  features: — (i)  Large  vascular  channels;  and  (ii)  matrix  con- 
taining irregular  spaces  and  branching  processes,  not,  however, 
sufl&ciently  well  organised  to  be  designated  lacunae.  In  the  greater 
part  it  is  coarsely  granular,  the  matrix  being  arranged  often  in  more 
or  less  spherical  bodies  of  varying  sizes.  At  the  periphery  there  are 
manv  large  thickened  masses  of  hyperplasic  cementum,  the  enamel 
and  dentinal  teeth  systems  being  suppressed. 

In  Fig.  345  it  is  seen  that  the  neoplasm  bears  some  resemblance  to 
plici-dentine.  Many  dentinal  systems  are  present,  with  very 
granular  dentine  matrix  and  radiating  tubes.  Cementum  and 
enamel  are  absent. 

Composite  Odontomes 

Origin. — Aberrations  and  abnormahties  in  the  development  of 
the  whole  or  part  of  the  constituents  of  the  tooth  germ.  Apparently 
they  are  confined  to  man,  but  they  are  very  rare. 

Macroscopical  Appearances. — An  odontome  of  this  type,  recorded 
by  Dolamore,  appeared  in  the  right  molar  region  of  the  mandible 
of  a  male  aged  22  years.  Its  measurements  after  removal  were 
4.2  cm.  in  length,  2.8  cm.  in  depth,  and  1.6  cm.  in  width,  and 
total  weight  24.5  grammes.  This  makes  it  one  of  the  largest  ever 
described. 

''Clinical  History.— Tht  patient  stated  that  he  first  had  pain 
about  three  years  previous  to  his  visit  to  the  Hospital.  He  came 
under  the  impression  that  there  was  a  root  of  a  tooth  troubhng  him. 
There  had  been  swelHngs  which  came  and  went.  The  suppurative 
inflammation  which  occurs  almost  universally  around  these  odon- 
tomes when  they  'erupt,'  appears  to  be  due  to  the  density  of  their 
structure.  The  soft  structures  forming  the  lining  membranes  of 
their  sockets,  even  though  it  is  also  the  forming  organ,  can  have 
but  slight  'hold'  upon  them  and  readily  become  detached.  Hence 
they  become  more  comparable  to  sequestra  than  to  pulpless  teeth, 


392 


THE    ORAL   TISSUES 


in  which  there  remains,  through  the  cementum,  a  gradual  transition 
from  the  hving  cells  of  the  pericementum  to  the  dead  dentine. 

"'Appearance  in  situ. — The  molar  and  second  premolar  teeth  are 
absent  on   the  right  side,   the  first  premolar  root  remaining.     A 


.iMl^^,.,^, 

■H 

mt^  -f.  ^i  :  -^  # 

^ 

l[ 

Fig.  347. — A  compo'site 
odontome  from  region  of  a  third 
right  mandibular  molar. 


Fig.  348. — Another   aspect    of  same 
odontome  as  in  preceding  figure. 


roughened,  hard  surface  occupied  about  the  situation  of  the  second 
molar  tooth,  being  distinctly  posterior  to  the  normal  position  of  the 
first  molar.  A  pointed  probe  could  be  passed  vertically  downwards, 
at  the  anterior  surface  of  the  tumour,  to  a  great  depth.     At  t-he 


Fig.  349. — Composite  odontome,  with  portions  of  the  capsule  adherent  to 
it,  and  the  third  molar  placed  in  situ.  The  tumour  is  viewed  on  its  lingual 
aspect.  From  an  original  photograph.  Actual  size.  e.  Portion  which  was 
erupting;  w.   Crown  of  third  molar. 


posterior  margin  of  the  exposed  surface  the  probe  passed  in  a  slant- 
ing direction  downwards  and  backwards.  The  margins  of  the  gum 
were  slightly  inflamed,  and  there  was  a  slight  amount  of  pus.  The 
two  surfaces  of  the  mandible  were  markedly  protuberant,  the  en- 


ODONTOMES  AND  ODONTOCELES 


393 


largement  extending  from  the  anterior  margin  of  the  tumour  towards 
the  angle. 


Fig.  350. — A  composite  odontome.      Prepared  by  grinding.      Unstained. 
Magnified  50  times.      E.  Enamel;  d.   Dentine;  o.   Osseous  material. 

"Removal. — A  curved  root  elevator,   passed  down  the  anterior 
margin,  slowly  levered  the  mass  out  of  its  bed,  gouging  out  with  it, 


394  THE    ORAL    TISSUES 

and  adherent  to  it,  a  portion  of  a  fibrous-like  capsule.  On  examina- 
tion, this  capsule  and  the  overlying  odontome  showed  on  the  lower 
and  outer  posterior  portion  the  imprint  of  a  molar  tooth.  This 
was  found  implanted  in  the  wall  of  the  'socket'  of  the  odontome, 
w^hence  it  was  readily  removed  with  an  upper  root  forceps.  The 
remainder  of  the  capsule  gave  to  the  'socket'  the  'velvety-like  lining' 
mentioned  by  Jordan  Lloyd,  in  a  case  he  has  described. 

The  size  and  weight  of  the  odontome,  and  the  comparative  ease 
with  which  the  tumour  could  be  removed  with  the  elevator  were 
outstanding  features  of  the  case." 

HISTOLOGY 

The  periphery  of  this  composite  odontome  is  made  up  of  fine-tubed 
dentine,  the  constituents  of  which  are  arranged  in  a  curiously  cen- 
tripetal fashion.  Thus,  instead  of  running  from  within  out,  as 
in  an  ordinary  manner,  these  pass  from  without  inwards,  some- 
times for  a  considerable  distance.  The  centre  of  the  growth  con- 
tains many  small,  irregular  islands  of  enamel.  Traces  of  absorption 
can  be  seen,  where  dark  bands  of  enamel  have  been  deposited  in  the 
spaces  in  the  dentine  matrix.  Interglobular  spaces  very  frequently 
abound. 

The  "osseous"  material  (Fig.  354)  which  composes  the  great  part 
of  the  growth  is  probably  merety  dentine  matrix  full  of  irregular, 
interglobular  spaces  and  canals.  No  cementum  as  such  exists; 
repeated  examinations  of  the  section  made  transversely  to  the  body 
of  the  odontome  have  failed  to  show  lacunae  and  canaliculi.  In 
one  place,  the  appearances  represented  by  a  crude  form  of  plici- 
dentine  may  be  noted. 

An  interesting  and  valuable  feature  of  this  tumour  in  the  presence 
of  its  fibrous  capsule  (Fig.  355).  Sections  of  this  reveal  several 
structures.  First,  the  soft  investing  tissues  are  made  up  of  small 
round  cells  with  one,  and  sometimes  two,  large  round  nuclei  in  their 
interiors,  also  long  fusiform  branching  cells  containing  elongated 
flattened  nuclei,  all  embedded  in  a  delicate  white  connective  tissue 
stroma.  Blood-vessels  abound,  and  are  more  numerously  distri- . 
buted  at  the  surface,  directed  towards  the  body  of  the  tumour. 

Sections  have  been  cut  in  which  the  relationship  of  the  bone  and 
capsule  have  not  been  disturbed.  The  result  shows  the  probable 
method  of  formation  of-  the  dentinal  substance  (Fig.  356).  At  the 
attached  maigin  of  the  capsule,  multitudes  of  osteoblasts  cohere  to 


ODONTOMES    AND    ODONTOCELES 


395 


Fig.  351. — Composite  odontome.  Ihe  section  is  a  portion  of  the  periphery 
of  the  growth,  the  dentinal  tubes  running  outwards  to  the  left,  the  remainder 
consisting  of  amorphous  dentine  matrix  with  absorption  areas  intervening. 
Prepared  as  in  Fig.  343.  Unstained.  Magnified  45  times,  d.  Dentine;  o. 
Osseous  material. 


Fig.  352. — Same  a.s  the  preceding   li^iurc,   hut   from   another  portion  of  the 
periphery.      Prepared  as  in  Fig.  343.      Unstained.      Magnified  45  times. 


396  THE    ORAL    TISSUES 

the  margin  of  the  dentogenetic  zone,  or  what  corresponds  to  this 
zone  of  formed  but  uncalcified  tissue  in  developing  dentine.  This  is 
a  clear,  translucent  band,  in  which  are  found  not  only  the  familiar 
calcospherite  spherules,  but  also  rudimentary  empty  tubes  (Fig. 
357).  The  osteoblasts  are  closely  placed  side  by  side,  and  are  seen, 
here  and  there,  to  be  embedded  in  cloudlike  masses  of  amorphous 
stained  albuminous  material.  Osteoclasts  sometimes  mingle  with 
osteoblasts. 


Fig.  353. — Composite  odontome.  Shows  enamel  and  amorphous  dentine 
fused  together,  the  dark  masses  being  .the  highly  pigmented  enamel,  the  lighter 
portions  the  dentine.      Magnified  45  times,      e.  Enamel;  d.  Dentine. 


Here  there  are  apparently  direct  and  irrefutable  evidences  and 
proofs  that  round  cells,  osteoblastic  in  shape  and  nature,  are  the 
factors  concerned  in  the  building  up  of  dentine,  the  empty  tubes 
being  probably  the  remains  of  the  connective-tissue  stroma  of  the 
capsule.  Thus,  again,  are  corroborated,  in  an  instructive  and  un- 
looked-for manner,  the  hypotheses  which  would  relegate  to  the 
odontoblasts  of  the  pulp  a  more  important  function  than  dentine 
building,  and  assign  this  physiological  process  to  the  round  osteo- 
blastic cells  seen  on  the  surface  of  the  pulp,  as  well  as  on  the  free 
edge  of  the  fibrous  capsule  of  this  composite  odontome. 


ODONTOMES   AND    ODONTOCELES 


397 


Fig.  354- — To  show  the  amorphous,  irregular  character  of  the  dentine  comprising 
the  greater  part  of  the  body  of  the  odontoma.      Magnified  45  times. 


Fig.  355. — Capsule  in  silu. 
th^  lower  the  fibrous  tissue. 
A,  Albuminoid  material. 


The  upper  part  of  the  photograpli  is  dentine, 
Magnified  45  times,     d.   Dentine;   c.    Capsule; 


398 


THE    ORAL    TISSUES 


Fig.  356. 


-Same   as    the   preceding,  showing,    d.  Dentine,    c.  Capsule,    and   DZ. 
Dentogenetic  zone  intervening.      Magnified  240  times. 


Fig.  357. — The  same  as  the  preceding,  to  show  the  calcospherite  spherules  and 
empty  tubes  in  the  dentogenetic  zone;  below  which  are  dark  masses  (a)  of  deeply 
stained  albuminous  material.      Magnified  600  times. 


ODONTOMES  AND  ODONTOCELES  399 

ODONTOCELES 

Similar  clinically  to  odontomes,  but  differing  very  considerably 
in  a  pathological  and  pathogenetic  sense  are  the  odontoceles  or  tooth- 
cysts.  An  odontocele  differs  from  an  odontome,  which  is  a  tooth- 
tumour,  in  the  facts  that  it  is  dissimilar  in  origin,  and  that  the  tooth 
associated  with  it  shows  certain  structural  deviations  from  the 
normal,  in  which  loss  or  addition  of  tissue,  either  from  maldevelop- 
ment  or  as  a  result  of  inflammatory  action,  is  a  conspicuous  feature. 

Varieties. — (i)  Sub-capsular,  (ii)  Extra-capsular. 

INTRODUCTORY 

The  types  which  are  about  to  be  narrated,  possessing  a  few  com- 
mon characteristics  or  relationships,  are  very  dissimilar  from  a 
pathogenetic  point  of  view,  and,  at  the  same  time,  are  extremely 
remarkable  and  interesting.  They  serve  to  illustrate  the  belief 
that  greater  precision  is  required  of  dental  surgeons  when  describing 
certain  pathological  changes  that  may  take  place  in  the  osseous 
framework  of  the  maxillae  and  mandible. 

There  is  room  for  an  amplification  and  revision  of  the  nomencla- 
ture employed  in  the  subject  of  dental  pathology,  and  new  terms 
must  necessarily  be  introduced  to  more  accurately  represent  con- 
ditions as  knowledge  of  the  special  pathology  of  the  teeth  ad- 
vances. It  is  necessary  to  throw  some  light  on  the  obscurity  of 
the  origin  of  cysts  of  the  jaws,  and  to  ascertain  in  what  circum- 
stances or  through  what  agencies  fluid  is  produced  in  such  amount  as 
to  constitute  the  chief  clinical  characteristic.  Their  signs  and 
symptoms  are  unimportant  and  uninstructive,  but  the  morbid  condi- 
tions and  the  patho-histology  of  the  tissues  are  of  extraordinary 
significance.  If  the  deductions  arrived  at  are  inconclusive,  or 
open  to  another  construction,  allowance  must  be  made  for  the 
difficulties  attaching  to  the  research  and  to  the  great  mystery  sur- 
rounding the  unique  display  of  morbid  phenomena. 

It  will  be  found  that  odontoceles  can  be  divided  into  two  classes. 
Thus  one  would  be  designated  an  example  of  a  Sub-capsular  odon- 
tocele, and  the  other  of  an  Extra-capsular  odontocele.  They  merely 
fall  into  the  same  main  category  because,  in  the  opinion  of  the  au- 
thor, they  cannot  strictly  be  placed  under  any  other  classification. 

A  common  feature  here  is  the  existence  of  a  unilocular  cyst  in  the 
jaws,  containing  an  anomalous  tooth — non-erupted,  and  so-called 


400  THE    ORAL    TISSUES 

"encysted,"  disclosing  itself  in  adult  life.  It  is  incorrect  to  describe 
"a.  case  of  an  encysted  tooth;"  the  fact  that  it  is  imbedded  in  the 
bone  does  not  of  necessity  mean  a  disease  of  the  tooth  or  jaw,  but 
a  state  of  being  or  condition  in  which  the  tooth  happens  to  exist. 
One  is  led  to  understand,  from  the  pages  of  text-books  and  cur- 
rent hterature,  that  a  buried,  "imprisoned"  tooth,  as  it  is  somewhat 
fancifully  called  by  Roswell  Park  in  The  Principles  and  Practice 
of  Modern  Surgery,  1908,  may  induce  a  passive  or  active  reaction  to 
the  containing  tissues.  Thus  (i)  it  may,  usually,  remain  in  its 
uncommon  irregular  position  undisturbed,  unnoticed,  inert,  impacted 
or  otherwise  throughout  the  life  cycle  of  the  individual,  giving  rise 
to  no  signs  or  symptoms  of  anomaly;  or  (2),  it  may,  rarely,  originate 
a  tumour,  through  the  production  and  accumulation  of  a  fluid 
body  around  it.  Chnically,  when  a  tense,  fluctuating,  non-inflam- 
matory, painless  sweUing  of  the  jaw  presents  itself  for  diagnosis, 
either  a  dental  cyst  or  a  follicular  odontome  is  first  brought  to  mind. 
These  two,  and  especially  the  former,  are  the  commonest  cysts 
with  which  the  dental  surgeon  has  to  deal.  But  other  species  of 
cysts  may  occur  at  times,  and  it  is  possible  to  fully  enumerate  them 
in  their  probable  order  of  frequency. 

SPECIES    OF    CYSTS    OF  THE  JAWS,  BASED  ON  THEIR  PATHOLOGICAL 

VARIATIONS 

(i)  Dental  cysts. 

(2)  Eruption  cysts. 

(3)  Follicular  odontomes — simple  or  compound. 

(4)  Epithehal  odontomes  or  multilocular  cystic  tumours. 

(5)  Mucous  cysts  of  the  antrum. 

(6)  Odontoceles:  (a)  Sub-capsular,  (b)  Extra-capsular. 

(7)  Cystic  adenomata  of  the  antrum  and  gum. 

Of  the  varieties  of  odontoceles,  the  sub-capsular  form  occurs  in 
the  young — from  10  to  20,  the  extra-capsular  form  later  in  life. 
Two  illustrative  cases  follow. 

A 

A  Sub-capsular  Odontocele.     {The  case  of  Mr.  R.  L.) 

On  examination  of  the  mouth  a  large,  smooth,  bluish,  fluctuating, 
painless  distension  of  the  bone  was  seen  occupying  the  right  canine 
region  of  the  mandible.     Its  presence  had  been  detected  subjec- 


ODONTOMES  AND  ODONTOCELES 


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402  THE    ORAL    TISSUES 

tively  only  five  weeks  previously.  The  canine  was  missing,  and 
there  was  no  history  of  its  having  been  extracted,  though  several 
teeth  had  been  removed  and  a  denture  was  being  worn.  The  first 
premolar  was  almost  in  contact  with  the  distal  surface  of  the  second 
incisor.  The  corresponding  tooth  was  not  in  evidence,  but  both 
left  canines  were  erupted  in  correct  alignment  with  the  dental 
arches.  A  cyst  was  diagnosed.  Radiographs  disclosed  the  following 
condition  of  the  parts:  At  the  base  of  an  extensive  cavity  in  the 
bone,  measuring  2.5  cm.  by  2  cm.  by  1.5  cm.,  was  a  canine,  non- 
erupted,  non-impacted,  non-absorbed.  It  was  placed  vertically 
in  the  jaw,  its  crown  pointing  upwards  and  extending  into  a  some- 
what triangular  hollow,  produced  by  the  divergency  of  the  roots  of 
the  second  incisor  and  first  premolar.  Examination  of  these  roots 
showed  no  visible  areas  of  absorption  whatever,  though  the  latter 
appeared  to  be  twisted.  On  inspecting  the  radiograph  of  the  canine 
it  was  at  once  apparent  that  there  was  a  loss  of  substance — i.e., 
enamel  and  dentine — at  the  summit  of  the  cusp.  It  was  possible 
to  trace  a  direct  line  of  continuity  between  the  cystic  contents  out- 
side the  tooth  and  the  pulp  itself. 

On  excising  the  cyst  wall  there  was  no  venous  haemorrhage,  as 
had  been  anticipated  from  the  colour  of  the  tumour.  Instead,  the 
cystic  contents  were  deeply  discoloured  and  almost  black.  It  was 
this  that  had  imparted  the  blue  appearance  by  reflected  light  to 
the  oral  tissues,  a  phenomenon  similar  to  that  frequently  witnessed 
in  connection  with  hydroceles  of  the  tunica  vaginalis.  The  tooth 
was  removed  and  the  cyst  wall  dissected  out;  granulation  tissue  soon 
formed,  and  at  the  end  of  ten  months  healing  had  taken  place,  a 
mere  shallow  depression  on  the  surface  of  the  jaw  marking  the  site 
of  the  odontocele. 

The  tooth  was  at  once  carefully  tested  for  the  presence  or  absence 
of  Nasmyth's  membrane.  The  inner  layer  was  found,  but  no 
cellular  layer.  It  was  then  treated  by  the  Koch-Weil  method,  and 
the  section  showed  that  the  tip  of  the  crown  was  defective  and  its 
growth  had  never  been  completed.  There  was  no  absorption  of 
tissue.  A  hollow,  tube-shaped  core  occupied  the  vertical  axis  of 
the  upper  part  of  the  tooth.  Had  it  erupted  in  the  ordinary  manner 
it  is  impossible  to  guess  what  the  consequences  would  have  been. 
Soft  tissue,  composed  of  small  cells,  extended  vertically  into  the 
pulp  cavity,  and  also  slightly  laterally,  in  places,  into  the  dentine. 
The  pulp  itself  was  composed,  at  its  coronal  portion,  of  broken-down 
cells,    the    odontoblasts   were    unrecognizable,    the    nerve   bundles 


ODONTOMES    AND    ODONTOCELES 


403 


obliterated,  while  a  few  long  endothelial-like  cells  closely  applied 
in  bundles  represented  the  collapsed  and  shrunken  walls  of  the 
vascular  system.  It  is  impossible  for  anyone  to  say  what  had  hap- 
pened to  the  enamel  organ  at  that  part  which  was  going  to  form  the 
summit  of  the  crown.  It  could  not  have  been  due  to  septic  disease 
of  a  deciduous  predecessor,  for  one  would  then  probably  get  the 
whole  of  the  enamel  organ  deranged  with  regard  to  its  usual  func- 
tions. Apparently  there  was  a  sudden  cessation  of  the  work  of  the 
ameloblasts  at  that  spot,  leaving  not  only  a  breach  of  surface  but  a 
direct  opening  into  the  pulp  cavity.     After  suitable  preparation  the 


p  p 


Fig.  358. — Longitudinal  section  of  canine  described  in  text.  E.  Enamel; 
p.  Pulp  cavity;  pp.  Pulp  tissue  extending  laterally  into  dentine;  1.  Incisive  edge 
of  tooth.      Magnified  20  times. 

cyst  wall  was  microscopically  examined.  It  was  very  thin,  only 
measuring  0.25  to  0.75  mm.  Composed  of  firm  fibrous  tissue  it  had 
a  lining  of  numerous  soft,  large  epithelial  cells,  held  loosely  together 
by  a  frail  cementing  substance.  It  was  in  no  sense  a  compound 
epithelium,  as  seen  sometimes  in  both  dental  cysts  and  follicular 
odontomes,  nor  were  they  secretory  cells.  It  was,  probably,  the 
external  epithelium  of  the  enamel  organ  swollen  by  absorption  of 
cystic  fluid,  and  the  cyst  wall  was  nothing  more  nor  less  than  the 
dental  cap.su]e  itself. 

To  the  accident  of  the  presence  of  a  congenital  lesion  of  the  hard 


404  THE    ORAL    TISSUES 

parts  of  the  crown,  and  not  to  impaction  or  delayed  eruption, 
can  be  attributed  the  evolution  of  this  cyst.  Here  is,  then,  an 
example  of  a  sub-capsular  odontocele — i.e.,  a  cyst  originating 
beneath  the  capsule  or  follicle  of  an  abnormal  tooth,  as  a  result  of 
the  effusion  of  lymph  from  the  neighbouring  blood-vessels,  into  a 
potential  cavity  produced  by  a  developmental  defect  of  the  summit 
of  its  crown.  It  may  be  suggested  that  the  same  morbid  phenomena 
might  have  been  induced  by  serous  exudation  into  a  space  or  spaces 
of  a  vacuolated  follicle.  But  here  the  capsule  had  undergone  no 
such  retrogressive  metamorphosis  on  account  of  its  being  retained 
in  the  jaw,  as  already  mentioned.  Hence  the  opinion  that  a  cavity 
had  existed  through  something  unknown  happening  to  the  formative 
cells  of  the  enamel  organ  many  years  ago,  and  effusion  of  lymph 
into  the  cavity  thus  created. 

B 

An  Extra-capsular  Odontocele.^     {The  case  of  Dr.  C.  N.) 

Interesting  and  instructive  as  is  the  case  just  detailed,  the  second 
variety  of  odontocele  is  even  more  remarkable. 

Past  history:  The  maxillary  incisors  and  premolars  had  previously 
been  removed.  One  was  broken,  two  were  quite  sound,  and  caries 
was  present  in  the  rest;  the  sound  teeth  were  sacrificed  for  the 
purposes  of  giving  firmer  hold  to  a  bridge  which  was  to  be  con- 
structed. The  denture  was  worn  for  ten  years.  About  three  weeks 
before  the  tumour  "became  cystic" — to  quote  the  patient's  own 
words- — he  broke  the  plate  through  the  middle,  and  he  continued 
to  wear  it,  being  too  busy  to  have  it  attended  to.  He  believes  that 
the  movements  of  the  fractured  appliance  irritated  the  jaw,  and 
"stirred  the  latent  tumour  into  activity."  His  dentist  pointed  out 
to  him  ten  years  previously  that  the  permanent  maxillary  canine 
in  the  right  side  was  missing,  and  had  apparently  never  erupted. 

Present  history:  "The  patient's  attention  was  first  directed  to  a 
small  enlargement  of  his  cheek.  He  noticed  it  when  washing  his 
face,  being  conscious  that  the  right  cheek  was  fuller  than  the  left. 
On  feeling  it  more  carefully  he  could  make  out  a  round,  hard  promi- 
nence close  by,  and  at  the  same  level  as  the  right  ala  of  the  nose. 
His  first  impression  was  that  an  alveolar  abscess  was  forming,  but 

1  A  similar  case — the  second  to  be  recorded — was  detailed  by  Mr.  J.  Alan 
Forty  and  the  author  in  a  paper  presented  to  the  International  Dental  Congress. 
1914. 


ODONTOMES  AND  ODONTOCELES  405 

it  did  not  make  any  progress  in  the  way  of  'ripening.'  About  two 
weeks  later  a  little  swelling  appeared  in  the  mouth  in  the  angle 
between  the  upper  lip  and  the  gum,  and  in  the  region  of  the  second 
incisor  and  canine  tooth.  This  was  fluctuant,  and  the  patient 
thought  that  it  probably  contained  pus.  He  incised  it,  but  did 
not  evacuate  any  pus,  and  in  a  few  days  it  had  attained  the  same 
size  again.  He  then  called  in  a  brother  practitioner,  who  incised 
it  down  to  the  bone,  and  it  was  then  apparent  that  the  swelling  was  a 
cvst.  It  soon  filled  up  and  became  considerably  larger,  and  the 
patient  then  thought  it  advisable  to  consult  a  surgeon  with  the  view 
to  its  removal.  Up  to  this  point  there  was  no  pain  associated  with 
it  beyond  a  throbbing  in  the  gum  and  part  of  the  hard  palate." 


Fig.  359.  Fig.  360. 

Fig.  359. — A  right  maxillary  first  incisor  contained  in  an  extra-capsular  odonto- 
cele  in  a  boy  of  10  years.  Labial  aspect.  Shows  a  calcareous  nodule  attached  to 
the  enamel.      {Mr.  Alan  J.  Forty's  case.) 

Fig.  360. — Another  aspect  of  tooth  of  preceding  figure.  Shows  a  calcareous 
nodule  attached  to  the  enamel. 

"The  patient  saw  a  leading  operating  surgeon  who  examined  the 
cyst  and  advised  its  removal.  A  few  days  later  he  proceeded  to  do 
this,  and  on  dissecting  off  about  a  third  of  the  cyst  wall  he  found  it 
firmly  rooted  to  the  bone  of  the  maxilla.  He  sheared  off  the 
dissected  portion  of  the  cyst  close  to  the  bone  with  the  view  to  its 
pathological  examination  and  further  operative  treatment.  From 
the  clinical  appearance  he  was  of  the  opinion  that  the  tissue  was 
mahgnant  in  character.  Examination  was  made  of  the  detached 
portion,  and  on  the  patient's  return  two  days  later,  he  was  informed 
that  the  tumour  was  of  the  nature  of  a  myeloid  sarcoma.  This 
diagnosis,  however,  was  disputed  by  the  pathologist  who,  as  a 
personal  friend  of  the  patient,  was  called  in  to  give  an  opinion.  He 
was  very  emphatic  that  there  were  no  tissue  elements  to  warrant  a 
diagnosis  of  malignant  disease,  and  it  is  only  fair  to  the  operating 
surgeon  to  say  that  he  abandoned  the  diagnosis  of  myeloid  sarcoma, 
and  consented  to  perform  a  much  more  modified  operation  than  he 
originally  intended,  although  still  feeling  that  there  was  a  malignant 


4o6 


THE    ORAL    TISSUES 


element  in  the  case.  The  operation  decided  upon  was  to  remove  the 
affected  area  with  a  margin  of  healthy  tissue  around  it.  This  was 
done,  a  wedge-shaped  portion  of  the  upper  jaw  being  removed,  and 
a  considerable  part  of  the  bone  of  the  anterior  wall  of  the  antrum 
included,  the  membrane  being  left.  The  cavity  in  the  mouth  healed 
up  without  any  diflficulty,  although  the  antrum  became  affected  and 
necessitated  douching  through  the  nose.  Eventually  the  wound 
closed  completely,  and  the  mouth  has  remained  sound  and  well 
after  a  period  of  twelve  months."     (Patient's  report.) 

Appearance  of  the  tumour:  The  specimen  consisted  of  a  V-shaped 
piece  of  tissue  bounded  internally  by  the  median  line  of  the  palate, 
and  externallv  bv  a  line  running  backwards  and  inwards  through 


CM 


Fig.  .361.  Fig.  362. 

Fig.  361. — Extra-capsular  odontocele,  as  viewed  from  mesial  aspect;  p. 
Palatal  surface;  L.  Labial  surface,  where  fluid  accumulated;  c.  Canine;  cm. 
Calcified  raass. 

Fig.  362. — Tooth  everted  from  its  surroundings  to  show  calcified  nodule  (n) 
attached  to  surface  of  crown. 

the  premolar  region.  Its  width  in  front  was  3.5  cm.  The  labial 
aspect  showed  an  opening  in  the  alveolar  process  22.5  mm.  long, 
9  mm.  wide,  the  lower  margin  being  placed  6  to  9  mm.  from  the 
free  edge  of  the  alveolar  process.  It  was  made  by  the  incision  for 
the  evacuation  of  the  cystic  fluid.  At  its  base,  and  at  a  distance  of 
about  4  mm.  from  the  surface,  lay  a  calcified  mass.  The  main 
object,  in  the  preparation  was  a  canine  fully  formed  and  well  devel- 
oped, 25  mm.  in  length.  Its  crown  was  almost  entirely  embedded 
in  a  solid  mass  of  brittle,  calcified  material,  which  was  yellowish 
in  colour  and  partly  translucent  by  reflected  fight.  During  the 
digital  disturbances  consequent  on  the  operation  this  calcified  cap 
had  obviously  been  dislodged  from  the  position  it  had  occupied  for 
many  years  and  had  become  detached,  and  the  crown  of  the  tooth 
was  shefled  out  from  it  with  the  exception  of  a  smaU  excrescence, 


ODONTOMES  AND  ODONTOCELES 


407 


which,  still  adhering  to  its  distal  aspect,  gave  the  clue  to  the  patho- 
logical conditions  which  had  been  occurring.  The  nodule  measured 
4  mm.  in  length,  the  dimensions  of  the  hard  cap  being  14  mm.  by 
12  mm.  There  were  no  marks  of  absorption  on  the  surface  of  the 
enamel.  Nasmyth's  membrane  was  present.  The  calcified  mass 
was  obviously  the  dental  capsule,  which  had  undergone  a  retro- 
gressive metamorphosis.  It  had  not  been  completely  infiltrated, 
as  portions  still  retained  their  fibrous  characters  (Fig.  361).  Patho- 
logical calcification  or  petrifaction  occurs  almost  without  exception 
only  in  degenerating,  dying,  or  dead  tissue  as  Hektoen  and  Riesman 


Fig.   363. — Photomicrograph  of  crown  of  tooth  described  in  text. 
c.   Calcified  nodule.      Magnified  45  times. 


E.    Enamel; 


record  (op.  cit.).  Thus  its  appearance  can  probably  be  explained 
by  the  fact  that  the  dental  capsule  of  the  unerupted  canine  had  died, 
and  formed  a  nidus  for  the  lime-salt  infiltration,  thus  differing  very 
greatly  from  the  follicle  in  the  preceding  Sub-capsular  odontocele. 
The  composition  of  the  hard  mass  was  found  to  be  calcium  car- 
bonate largely.  On  placing  a  fragment  under  the  microscope, 
and  allowing  a  weak  solution  of  hydrochloric  acid  to  run,  by  capillary 
attraction,  beneath  the  cover  glass,  bubbles  of  gas  were  immediately 
evolved,  the  residue  of  organic  material  presenting  an  amorphous 
structure  with  a  tendency  to  the  formation  of  a  pattern  of  spherules. 
Around  the  surface  of  this  calcified  capsule  was  developed  the  cyst, 


408  THE    ORAL    TISSUES 

and  what  was  apparently  the  "bone  of  the  jaw"  mentioned  in  the 
patient's  notes  was  its  exposed  surface.  Histologically  examined, 
the  soft  parts  consisted  chiefly  of  connective-tissue  fibres  with 
nmuerous  small  cells,  changed  connective-tissue  corpuscles,  tiny 
haemorrhages,  clusters  of  fat  cells,  blood-vessels,  and  a  small  amount 
of  bone  which  represented  all  the  remains  of  the  thinned  and  ex- 
panded external  alveolar  plate.  The  cyst  wall  was  lined  with  epi- 
thelium.    There  were  no  microscopic  signs  of  inflammation. 

Whence  came  the  cystic  fluid?  It  is  difficult  to  determine. 
Eliminating  every  possible  structural  element  in  the  gum  which 
could  give  rise  to  a  cyst,  it  might  be  conjectured  that  the  cells  of  the 
walls  of  certain  lymph  spaces  in  the  submucous  tissues  had  broken 
down,  and  produced,  by  rapid  multiplication,  the  cyst,  through  irri- 
tation from  the  friction  of  a  loose,  fractured  mechanical  appliance  on 
the  one  side,  and  the  hard  unyielding  surface  of  the  ossified  capsule 
on  the  other. 

At  first  sight  the  dental  condition  might  have  been  regarded  as  a 
calcified  follicular  odontome.  But  this  was  not  so.  For  the  cystic 
fluid  was  outside,  not  inside,  the  capsule,  which  was  not  expanded, 
but  remained,  in  spite  of  its  petrifaction,  closely  adherent  to  the 
surface  of  the  tooth.  Hence  it  is  an  extra-capsular  odontocele. 
Its  origin  may  be  explained  by  the  breaking  down  of  epithelium  or 
endothelium  in  the  soft  tissues  of  the  jaw  lying  between,  and  stimu- 
lated into  growth  by  the  pressure,  and  perhaps  friction,  of  two  hard, 
unyielding  substances. 

There  are  some  further  problems  surrounding  this  case  which  can 
never  possibly  be  solved :  The  age  of  the  patient  when  calcification  of 
the  capsule  took  place;  the  possibility  or  otherwise  that  this  calci- 
fication, acting  as  an  obstruction,  was  the  cause  of  the  non-eruption 
of  the  tooth;  the  histological  characteristics  of  the  actual  structures 
in  the  soft  superimposed  parts,  which,  on  breaking  down,  produced 
the  odontocele;  the  date  of  its  formation;  and  the  nature  of  the  still 
more  mysterious  forces  which  governed  the  impregnation  with 
lime  salts  of  the  dead  or  dying  follicle. 

The  fact  that  mechanical  agencies  play  a  not  inconsiderable  part 
in  the  production  of  disease  calls  for  no  special  comment.  And  teeth 
which  undergo  moliminous  eruption,  or  do  not  erupt  at  all,  as  is  so 
frequently  the  case  with  the  third  molars,  may  act  as  foreign  bodies 
and  produce  inflammation  and  absorption  of  the  surrounding  parts, 
and  even  give  rise  to  cystic  tumours  of  the  maxilla. 


CHAPTER  XVI 

ORAL  MICROBIOLOGY 

Introduction — Classification  of  plants — Classification  of  Bacteria  and 
Protozoa — Microscopic  examination  of  oral  material — Pathogenic 
organisms — The  Pyogenic  cocci — Filterable  viruses — Adventitious 
bacteria  of  the  mouth — Micro-organisms  of  dental  caries. 

INTRODUCTION 

In  contributing  a  chapter  on  Oral  Microbiology,  one  can  but  briefly 
outline  the  classification  and  characteristics  of  the  organisms  com- 
monly found  in  the  oral  cavity.  It  would  be  inexcusable  to  attempt 
the  presentation  of  more  than  the  dental  phase  of  the  subject,  there- 
fore the  reader  is  referred  to  standard  works  on  the  subject  of  Micro- 
biology, Bacteriology,  and  Protozoology  for  a  detailed  account  of 
the  micro-organisms. 

The  oral  cavity  is  a  fertile  field  for  the  development  of  various 
types  of  micro-organisms.  We  find  there  a  temperature  suitable  for 
the  growth  of  a  large  percentage  of  the  organisms,  substances 
supplying  nourishment,  a  sufficient  supply  of  moisture  and  oxygen. 
Furthermore  there  are  various  crypts  and  spaces  in  which  they  may 
develop  undisturbed.  The  organisms  manifestly  gain  access  by 
way  of  the  mouth,  being  carried  there  with  food,  drink,  instruments, 
etc.,  or,  they  may  be  carried  in  through  the  nasal  passages  with  the 
inspired  air.  These  organisms  may  be  transmitted  directly  from 
other  individuals.  The  investigator  possessing  this  knowledge  is 
not  surprised  at  the  variety  found,  but  rather  that  more  species 
are  not  encountered. 

Some  micro-organisms  do  not  find  a  suitable  environment,  and  they 
will  not  multiply  at  all,  or  but  to  a  very  slight  extent,  in  the  oral 
cavity.  Some  are  antagonistic  to  the  development  of  others. 
Foods,  drink  and  the  saHva  are  constantly  or  intermittently  not  only 
diluting  the  organisms,  but  carrying  many  of  them  along  the  pas- 
sages into  the  gastro-intestinal  tract,  causing  a  diminution  of  the 
numbers  and  also  changing,  to  some  extent,  the  types  found  in  a 
given  individual  from  day  to  day. 

409 


41 0  THE    ORAL    FLORA 

Many  of  the  organisms  present  are  of  no  pathological  importance, 
being  of  a  type  incapable  of  exerting  a  detrimental  action  on  the 
tissues.  Others,  while  possessing  no  pathogenesis  in  the  strict  sense 
of  the  word,  are  of  great  importance  to  the  dental  practitioner  and 
pathologist  owing  to  the  fact  that  they  play  an  important  part, 
either  directly  or  indirectly,  in  the  condition  known  as  dental  caries. 
Various  types  of  organisms  are  also  encountered,  which  are  capable 
of  producing  definite  infections  when  local  and  general  conditions 
such  as  will  admit  of  their  invading  the  tissues  exist. 

On  studying  microscopically  and  culturally,  the  flora  and  fauna 
of  the  oral  cavities  of  a  large  number  of  individuals,  the  investigator 
is  always  impressed  with  a  number  of  facts  of  interest  and  also  of 
great  import.     The  most  important  of  these  are  as  follows: 

(i)  The  number  of  organisms  in  the  oral  cavities  of  different 
individuals  varies  markedly. 

(2)  The  more  closely  associated  are  individuals,  the  more  nearly, 
other  things  being  equal,  does  the  micro-organismal  content  of  their 
oral  cavities  correspond. 

(3)  The  number  and  types  of  micro-organisms  vary  in  the  oral 
cavities  of  all  individuals  to  a  great  extent  according  to  environ- 
mental conditions,  food,  etc. 

(4)  The  micro-organismal  content  is  influenced  directly  by  the 
degree  of  cleanliness  the  individual  exercises  as  regards  his  oral 
cavity. 

(5)  However  cleanly  one  may  be,  it  is  impossible  to  remove  or 
prevent  the  growth  of.  all  micro-organisms. 

(6)  Certain  types  of  organisms  are  encountered  almost  univer- 
sally in  different  individuals. 

(7)  Micro-organisms  possessing  a  definite  pathogenicity  may  exist 
in  the  oral  cavity  of  an  individual  without  causing  any  untoward 
results. 

The  greater  number  of  the  micro-organisms  encountered  in  the 
oral  cavity  are  Bacteria.  Higher  Fungi  are  found,  a  few  varieties  of 
Yeasts,  and  several  varieties  of  organisms  of  various  types,  ordi- 
narily known  as  Moulds.  Some  of  the  latter  are  capable  of  producing 
pathogenic  conditions,  which,  however,  are  not  common.  The 
protozoa  have  not  been  studied  in  the  same  detail  as  bacteria. 
There  are,  however,  comparatively  few  varieties  present. 

Before  entering  into  a  discussion  of  the  various  types  of  organisms 
found  in  the  oral  cavity  and  their  significance,  it  is  essential  that  the 


ORAL    MICROBIOLOGY  41I 

student  be  possessed  with  some  knowledge  of  their  morphology  and 
physiology,  also  of  their  place  in  the  biological  world. 

Bacteria  are  microscopic,  unicellular  vegetable  organisms,  oc- 
curring either  as  small  spheres,  straight  or  curved  rods,  or  as  long 
threads,  motile  or  non-motile,  some  forming  endospores,  multiplying 
by  a  process  of  transverse  division  or  fission,  devoid  of  chlorophyll, 
and  nourished  by  a  process  of  osmosis. 

These  organisms  are  very  minute  and  the  individual  cells  can  only 
be  seen  when  magnified  several  hundred  diameters;  they  average 
in  size  from  about  0.4  to  1.5  ^  in  diameter  for  the  spherical  forms, 
and  from  0.8  to  4  //  long  for  the  rod  shaped,  and  15  to  30  ^u  in  length 
for  the  thread  forms. 

Each  individual  organism  consists  of  a  single  cell:  in  no  instances 
are  bacteria  multicellular.  The  majority  of  the  organisms  classi- 
fied as  bacteria  are  vegetable,  and  therefore  belong  to  the  plant 
kingdom.  The  morphological  classification  basically  depends  on  the 
shape  of  the  individual  cells,  as  will  be  seen  by  consulting  the 
list  given,  page  413.  They  are  devoid  of  cMorophyll,  the  green 
colouring  matter  of  many  plants,  which  enables  them  to  obtain 
nourishment,  at  least  partially,  from  inorganic  sources;  consequently 
they  are  nourished  by  a  process  of  osmosis.  They  divide  by  a  pro- 
cess of  transverse  division  or  fission:  therefore  they  are  classed  with 
the  Schizophyta,  or  fission  plants  under  the  name  of  Schizomy- 
cetes  or  fission  fungi,  belonging  to  the  group  of  plants  known  as 
Cryptogams. 

Certain  of  the  bacteria  possess  long  slender  appendages,  which 
can  only  be  demonstrated  by  special  methods  of  staining,  called 
flagella.  These  are  constantly  in  motion,  and  cause  the  organisms  to 
move  about  in  the  substratum  in  which  they  are  developing.  The 
rapidity  and  mode  of  the  movements  give  to  the  organisms  a 
characteristic  type  of  motility;  many  non-flagellated  bacteria  present 
an  oscillatory  motion  known  as  Brownian  or  Brunonian  motion. 

Certain  bacteria  produce  small  oval  or  spherical,  highly  refractile, 
glistening  bodies,  known  as  spores  or  endospores.  When  certain  con- 
ditions are  present,  as  deficient  nutritive  material,  or  moisture,  or 
the  presence  of  substances  exerting  a  detrimental  action  on  the  or- 
ganism, small  granules  (the  sporogenic  granules)  appear  within  the 
cellular  protoplasm;  these  granules  gradually  coalesce  in  the  centre  or 
at  one  enrl  of  a  cell  forming  the  endospore.  These  endospores  lie 
dormant  until  conditions  are  favorable  for  their  development,  when 
they  germinate  and  pass  into  the  vegetative  stage.     The  vegetative 


412  THE    ORAL   FLORA 

cell  is  capable  of  multiplying  by  a  process  of  transverse  division. 
The  statement  is  frequently  encountered  that  some  bacteria  repro- 
duce by  sporulation;  this  statement  is,  according  to  our  present 
views,  erroneous. 

In  cultures  of  certain  bacteria,  cells  are  found  which  vary  markedly 
from  the  normal  types  in  size  and  shape.  In  some  instances  these  cells 
have  been  called  Arthros pores,  the  claim  being  made  that  they  play 
a  part  in  the  reproduction  of  the  organisms.  These  cells  are  in  all 
probability  involution  forms  of  the  organism,  due  to  osmotic  dis- 
turbances, and  not  true  arthrospores. 

Yeasts  are  small  oval  or  spherical  vegetable  organisms  which  repro- 
duce by  a  process  of  budding,  at  times  producing  small  spherical  or 
oval  bodies  known  as  ascospores.  They  are  classed  under  the  Eumy- 
cetes  with  the  group  of  Ascomycetes. 

The  Moulds  include  a  group  of  organisms  of  various  types  whose 
common  characteristics  lie  in  the  fact  that  they  develop  from  spores 
forming  a  mycelium,  which  is  the  body  of  the  fungus,  to  which  are 
attached  hyphae  of  various  types,  at  the  ends  of  which  outgrowths 
appear  which  carry  the  spores  or  conidia,  endospores  or  gonidia;  or 
bodies  are  formed  by  the  union  of  elements  at  the  end  of  two  hyphse, 
joining  together,  known  as  zygospores. 

There  is  a  group  of  organisms  allied  to  the  yeasts  and  moulds 
which  have  resisted  all  attempts  at  proper  classification,  and  are 
therefore  grouped  under  the  head  of  Fungi  Imperfecti.  Many  mem- 
bers of  this  group  are  of  great  import  from  a  pathological  point  of 
view.     Some  are  encountered  in  the  oral  cavity. 

The  following  will  give  the  student  an  insight  into  the  relation- 
ships existing  between  the  various  plant  groups. 

CLASSIFICATION    OF    PLANTS^ 

(A)  Spermatogams,  Spermatophytes,  or  Phanerogams,  the  seed 
plants.  In  this  group  are  included  the  higher  plants;  all  those 
reproducing  by  dissemination  of  seeds. 

(B)  Cryptogams,  including  those  plants  reproducing  by  means  of 
endospores  or  gonidia,  exospores  or  conidia,  budding  and  by  trans- 
verse division  of  fission. 

Classification  of  Cryptogams  with  special  reference  to  those  organ- 
isms of  importance  from  a  pathological  viewpoint. 
Division  I.  Myxothallophyta,  the  slime  fungi. 


ORAL    MICROBIOLOGY  413 

Division  II.  Euthallophyta,  the  true  thallophytes,  namely  those 
plants  which  cannot  be  differentiated  into  root,  stem  and  leaf. 

(A)  Schizophyta,  fission  plants: — ■ 

a.  Schizomycetes,  fission  fungi,  cleft  fungi,  or  bacteria, 
h.  SchizophycecB,  cyanophycece.  or  blue  green  algae. 

(B)  Phycomycetes,  fungi  resembling  algae: — ■ 

a.  Ooniycetes,  aquatic,  not  important, 

b.  Zygomycetes,  including  many  of  the  important  moulds 
producing  zygospores. 

(C)  Eumycetes,  true  fungi: — • 

a.  Ascomycetes,   important  as  certain  pathogenic  yeasts  and 

allied  organisms  are  included  in  this  group, 
h.  Basidiomycetes, 

c.  Fungi  imperfecti,  important.  This  group  includes  a 
number  of  types,  some  pathogenic,  the  characteristics  of 
which  are  of  such  a  nature  as  to  render  it  difficult  to 
properly  classify  them. 

Division  III.  Thallophyta,  including  green,  brown,  and  red  algae, 

not  important. 
Division  IV.  Bryophyta,   including    liverworts   and  mosses,  not 

important. 
Division  V.  Pteridophyta,  including  the  ferns  and  other  plants  as 

lycopodium  and  adder's  tongue,  not  important. 

CLASSIFICATION    OF    BACTERIA 

Order:  Schizomycetes 

A.  Sub-order:  EuhacteriacecB  (without  coloured  granules  in  cell  con- 
tents; uncoloured  except  in  a  few  species,  which  may  produce  a 
soluble  or  an  insoluble  pigment). 
I.  Family:   Coccacece    (globular,   becoming  slightly  elongated 
before    cell    division;    cell    division   in   one,    two   or   three 
directions). 
(a)  Genus:  Streptococcus    (cell    division    in    one    direction, 

united  in  chains,  non-flagellated). 
ib)   Genus:  Micrococcus  (cell  division  in  one,  two  or  three 
directions  with  separation  of  the  cells,  non-flagellated). 

(c)  Genus:  Sarcina  (cell  division  in  three  directions,  united 
in  packets  of  eight,  non-flagellated). 

(d)  Genus:  Planococcus   (cell  division  in  one,  two  or  three 
directions,  cells  separate;  flagellated). 


414  THE    ORAL    FLORA 

(e)    Genus :  Piano  sarcina  (cell  division  in  one,  two  or  three 
directions,  cells  united  in  packets  of  eight;  flagellated). 
II.  Family:  Bacteriacea    (cells    straight,   cylindrical,   short   or 

long  rods  without  a  sheath,  non-branching;  flagella  present 

or  absent;  endospores  present  or  absent). 

(c)  Genus:  Bacterium  (cells  straight,  cylindrical,  short  or 
long  rods,  non-motile;  flagella  absent;  endospores  pres- 
ent or  absent). 

{b)  Genus:  Bacillus  (cells  straight,  cylindrical,  short  or  long 
rods,  motile,  with  peritrichous  flagella  varying  in  num- 
ber, endospores  present  or  absent). 

(c)  Genus:  Pseudomonas  (cells  straight,  cylindrical,  short  or 
long  rods,  occasionally  in  short  filaments;  motile;  with 
flagella  arranged  at  one  end,  monotrichous  or  lopho- 
trichous;  endospores  known  in  but  a  few  species). 

III.  Family:  SpirillacecB  (cells  more  or  less  curved;  rigid  or 
flexile,  cell  division  transverse  to  long  axis  of  cell;  flagella 
present  or  absent,  monotrichous  or  lophotrichous). 

(o)  Genus:  Spirosoma  (cells  rigid,  non-motile,  without 
flagella) . 

{h)  Genus:  Microspira  (cells  rigid,  motile,  with  one  or  two 
polar  flagella). 

(c)  Genus:  Spirillum  (cells  rigid,  motile,  possess  a  tuft  of 
polar  flagella). 

{d)  Genus:  Spirochceta  (cells  flexile,  sinuous,  corkscrew-like, 
do  not  possess  flagella  but  are  motile,  usually  actively; 
motility  due  to  undulations  of  membrane).  (The 
majority,  if  not  all,  of  the  Spirochaeta  divide  by  fa 
different  process  than  the  bacteria  and  should  [be 
classed  with  the  Protozoa  under  the  Flagellata.  Genus: 
Treponema) . 

IV.  Family:  Mycobacteriacece  (cells  straight,  short  or  long,  cylin- 
dric,  clavate,  cuneate  in  form,  at  times  showing  a  true 
branching,  or  as  long,  branched  mycelial  filaments;  no  sheath; 
without  endospores,  but  at  times  forming  gonidia-like  bod- 
ies due  to  transverse  segmentation  of  cells). 

(a)  Genus :  Mycobacterium  (cells  commonly  short,  cylindrical 
rods,  sometimes  bent  and  irregularly  swollen,  clavate  or 
cuneate;  may  present  Y-shaped  forms  or  longer  fila- 
ments with  true  branchings;  produce  short  coccoid  ele- 
ments which  may  be  gonidia). 


ORAL    MICROBIOLOGY  415 

(b)  Genus:  Streptothrix  (cells  commonly  long  branched 
filaments;  produce  gonidia-like  bodies;  form  aerial 
hyphae  in  cultures;  causing  resemblance  to  moulds). 

V.  Family:   Chlamydobaderiacece  (cells  in  the  foi-m  of  filaments, 
and     surrounded     by     a    distinct    sheath;    cell    division 
transverse  or  in  three  directions,  resulting  in  formation  of 
gonidia-like  bodies  which  may  or  may  not  be  motile), 
(a)  Genus:  Leptothrix   (filaments      unbranched;      division 
transverse) . 
.    {b)   Genus:  Phragmidiothrix   (filaments   unbranched;   divi- 
sions in  three  directions;  sheath  scarcely  visible). 

(c)  Genus:  Crenothrix  (filaments  unbranched,  division  in 
three  directions;  sheath  distinct). 

{d)  Genus:  C/aio^Anx  (filaments  show  false  branching) . 
B.  Sub-order:  Thiobacteriacece  (cells  show  presence  of  coloured  gran- 
ules, or  sometimes  diffuse  colouring  red  or  violet). 
I.  Family:  Beggiatoacece  (filamentous;  with  or  without  sheath; 
motile  or  non-motile  sulphur  granules  in  cell  contents;  go- 
nidia  formation  not  known). 
II.  Family:  RhodobacteriacecB    (cells   irregular,    globular,    oval, 
cylindrical,  non-filamentous;  contents  show  the  presence  of 
sulphur  granules  or  bacterio-purpurin,  red  or  violet). 

PROTOZOA 

The  Protozoa  are  microscopic,  unicellular,  animal  organisms  of 
various  forms.     Some  occur  in  the  oral  cavity,  but  have  not  been 
studied  in  the  same  detail  as  the  Bacteria.     The  most  important  are 
the  following: 
Of  the  Flagellata: 

Genus:  Treponemata,  several  species. 
Genus:  Trichomonas ,  one  or  more  species. 
Of  the  Sarcodina: 

Genus:  Endamceba;  endamoeba  gingivahs  of  Gros. 
Other  endamoeba? 

MICROSCOPIC  EXAMINATION  OF  ORAL  MATERIAL 

Various  representatives  of  the  different  groups,  in  the  foregoing 
classification,  will  be  observed  when  one  mounts  and  examines 
microsco[)ically    preparations    of  scrapings  from  the  oral  mucous 


4i6 


THE    ORAL    FLORA 


E  C 


Fig.  364. — The  micro-organisms  from  a  healthy  mouth  direct.  Stained  by 
Gram's  method.  Magnified  800  times.  E.G.  Squamous  epithehal  cell  from 
surface  of  cheek;  B.  Rod-shaped  form,  probably  Bacillus  biiccalis  ?}iaxim:is;  t. 
Thread  form;  d.   Diplococci,  probably  Streptococcus  brevis;  s.   Spiral  form. 


E  C 


Fig.  365. — From     same    preparation.     Balsam    preparation,     e.g.   Epithelial 
cell;    X.   Nucleus    of    partially-digested    epithehal    cell;    T.  Thread    forms;    l.r. 

Leptothrix  racemosa. 


ORAL    MICROBIOLOGY 


417 


membranes,  especially  in  the  buccal  and  alveolar  sulci;  from  the 
surface  of  the  teeth;  collections  of  food  debris  on  the  teeth,  or  in 
protected  surfaces;  soft  salivary  calculus;  exudates  from  alveolar 
abscesses,  gingival  infections  and  various  pathological  processes  in 
different  parts  of  the  oral  cavity. 

Suppose  a  mucinous  plaque,  from  the  surface  of  a  tooth,  is 
selected  for  study,  and  shde  preparations  are  made,  both  fresh  and 
stained,  for  examination.  Examination  of  such  stained  prepara- 
tions  will   reveal  the  presence  of  long  thread-like  organisms,  some 


Fig.  366. — From  similar  preparation  to  the  preceding.  Stained  by  Gram's 
method,  m.  Dense  mass  of  micro-organisms  from  edges  of  which  project :  t. 
Thread  forms;  and  B.  Bacillus  forms;  N.  Nucleus  of  partially-digested  epithelial 
cell. 


stained  in  a  homogeneous  manner,  others  presenting  small  granules. 
Some  of  these  are  species  of  the  genus  leptothrix,  others  the  genus 
cladothrix  of  the  sheathed  bacteria,  while  still  others  are  members 
of,  the  streptothrix  group.  Various  types  of  rod-shaped  organisms 
may  be  found,  short  and  long  rods,  some  grouped  singly  others  in 
chains.  Numerous  types  of  spherical  cells  (cocci),  some  of  which 
present  a  characteristic  grouping,  are  always  found.  If  fresh,  moist 
material,  either  slide  or  hanging-drop  preparation,  is  examined,  some 
of  the  organisms  will  be  found  to  possess  the  power  of  locomotion 
and  move  slowly  or  actively  about  the  microsco[)ic  field. 
27 


4i8 


THE    ORAL    FLORA 


Preparations  made  from  the  alveolar  sulci  of  unclean  mouths,  or 
from  pathological  conditions  may  contain  bacteria  of  the  same  types 
as  described  above.  In  addition  there  will  be  found  squamous 
epithelial  cells  in  various  stages  of  disintegration,  some  containing 
bacteria;  mononuclear  and  polynuclear  leucocytes,  frequently 
present  in  sufficient  numbers  to  constitute  pus;  other  types  of  bac- 
teria, as  fusiform  bacilli,  short  and  long  chain  streptococci;  protozoa 
and  various  types  of  spirochseta  or  treponemata,  which  are  readily 
recognised  by  the  fact  that  they  appear  as  long  sinuously  curved 


Fig.   367. — The  scrapings  from  an  approximal  surface  of  a  tooth.     Shows  all  the 
typical  forms  found  in  the  mouth.      {Photomicrograph  by  Leon  Williams.) 

rods  pointed  at  the  ends,  and  the  Endamoeba  gingivalis  recognised 
as  a  unicellular  organism,  many  times  the  size  of  the  largest  coccus, 
circular  or  irregular  in  outline  containing  in  the  protoplasm  granular 
debris,  bacteria,  other  cells  and  one  or  more  nucleus-like  bodies. 
Examination  of  fresh  moist  preparations  of  such  material  will  demon- 
strate the  fact  that  some  of  the  bacteria  present  are  actively 
motile;  the  spirochsetse  present  a  rapid  sinuous  or  rotary  movement, 
while  the  endamoebae  move  by  means  of  pseudopods,  producing  the 
characteristic  amoeboid  motion. 

Preparations  examined,  microscopically,  by  aid  of  one  or  another 


ORAL    MICROBIOLOGY 


419 


of  the  dark  field  illuminators,  in  which  the  field  is  dark  and  the  cells 
and  other  particles  highly  illuminated,  will  reveal  the  motile  organ- 
isms moving  about  in  various  ways,  some  so  characteristically  as 
to  enable  the  observer  to  establish  their  identity.  This  method  of 
study  will  in  many  instances  reveal  the  presence  of  organisms  not 
readily  demonstrated  in  stained  preparations,  notably  certain 
flagellates  the  significance  of  which  has  not  as  yet  been  determined. 

Many  expect  a  microbiologist  to  be  able  to  identify  and  name  the 
various  species  of  micro-organisms,  from  their  microscopic  appear- 
ance; this  is  impossible  excepting  in  a  few  instances.  The  identi- 
fication of  a  species  is  an  entirely  different  proposition  from  iden- 
tifying a  family  or  genus;  species  closely  allied  morphologically 
frequently  show  material  differences  when  studied  individually 
under  appropriate  conditions. 

For  the  purpose  of  identifying  species  it  is  absolutely  essential, 
excepting  in  a  few  instances,  that  the  organisms  be  isolated  one 
from  another  in  what  is  known  as  a  pure  culture,  i.e.,  a  culture 
which  contains  but  one  strain  of  a  species.  Individual  organisms 
are  identified  by  correlating  the  information  obtained  by  observing 
the  morphological  characteristics;  the  mode  of  growth  on  various 
artificial  media;  the  action  on  various  proteins,  carbohydrates,  fats 
and  other  substances;  the  relation  of  growth  to  various  physical 
conditions,  such  as  oxygen  and  temperature  relationships;  pigment 
production  and  the  determination  of  whether  or  not  the  organism 
is  capable  of  producing  disease. 

The  methods  of  separating  bacteria  in  pure  cultures  from  mixtures 
containing  different  species,  and  methods  employed  in  identifying 
those  isolated,  are  dealt  with  in  works  on  bacteriological  technique; 
to  which  the  student  is  referred  for  such  information. 

PATHOGENIC   ORGANISMS 

The  following  is  a  fist  of  the  most  important  pathogenic  bacteria 
and  other  fungi  encountered  in  the  oral  cavity: 

Micrococci: 

Micrococcus    aureus.       Synonym:     Staphylococcus    pyogenes 

aureus. 
Micrococcus  albus.     Synonym:  Staphylococcus  pyogenes  albus. 
Micrococcus     citreus.       Synonym:     Streptococcus     pyogenes 

citrcus. 


420  THE    ORAL    FLORA 

Diplococci: 

Micrococcus  catarrhalis. 

Meningococcus.     Synonym:     Diplococcus     intracellularis. 
Gonococcus.     Synonym:  Diplococcus  gonorrhoeae. 
Pneumococcus.     Synonym:  Diplococcus  pneumoniae. 
Tetracocci: 

Micrococcus  tetragenus.     Synonym:  Sarcina  tetragena. 
Streptococci: 

Haemolytic  type. 

Streptococcus  pyogenes. 
Streptococcus  anginosus. 
Non-haemolytic  type. 

Streptococcus  viridans:  Produces  methaemoglobin. 
Streptococcus  salivarius. 
Bacilli: 

Bacillus  diphtheriee.     Synonym:  Bacterium  diphtheriticum. 
Bacillus    pseudo-diphtheriae.     Synonym:    Bacterium    pseudo- 

diphtheriticum. 
Bacillus  fusiformis.     Synonym:  Mycobacterium  fusiforme. 
Bacillus  tuberculosis.     Synonym:  Bacterium  or  Mycobacterium 

tuberculosum. 
Bacillus  mallei.     Glanders  bacillus. 
Bacillus  mucosus  capsulatus.     Synonym:  Bacterium  mucosum 

capsulatum. 
Bacillus  influenzise. 
Bacillus  anthracis. 
Bacillus  aerogenes  capsulatus. 
Bacillus  tetani. 
Streptothricece: 

Streptothrix  bovis.     Synonym:  Streptothrix  actinomyces,  Ac- 
tinomyces bovis  "The  Ray  fungus." 
Streptothrix  hominis. 
Streptothrix  buccalis. 
Spirochcetce.     Synonym:  Treponemata. 

Spirochaeta  pallida  or  Treponema  pallidum. 
Spirochaeta  vincenti  or  Treponema  vincenti. 
Spirochaeta  of  the  mouth,  as  Treponema  macro-  and    micro- 
dentium  and  others. 
Higher  Fungi: 

Ascomycetes. 
Blastomyces. 


ORAL   MICROBIOLOGY  42 1 

Oidium  albicans. 
Zygomycetes. 

Rhizopus  nigrans. 
Sporothricum  hominis. 
Protozoa: 

Sarcodina. 

Endamoeba  gingivalis. 
Flagellata. 

Trichomonas.     (Significance  questionable.) 

Spirochasta  or  Treponemata.     (See  bacteria.) 

THE   PYOGENIC    COCCI 

Staphylococci  pyogenetes,  or  Pyogenic  micrococci. 

A.  Micrococcus  aureus  or  Staphylococcus  pyogenes  aureus. 

B.  Micrococcus  citreus  or  Staphylococcus  pyogenes  citreus. 

C.  Micrococcus  albus  or  Staphylococcus  pyogenes  albus. 

The  presence  of  micrococci  in  pus  was  in  all  probability  first 
demonstrated  by  Pasteur ^  in  1880.  The  first  to  isolate  and  establish 
the  relation  of  the  most  important  member  of  the  group  to  suppura- 
tive processes  was  Rosenbach^  in  1884,  who  called  the  organism 
Staphylococcus  pyogenes  aureus. 

This  organism  is  widely  distributed,  being  commonly  found  upon 
the  external  surface  and  in  the  oral  and  nasal  cavities  of  man  and 
many  lower  animals;  it  is  not  uncommonly  found  in  the  aUmentary 
tract.  When  the  tissue  resistance  is  lowered,  either  locally,  due  to 
the  action  of  some  irritant;  or  generally,  due  to  over-strain,  malnu- 
trition or  some  constitutional  disease,  this  organism  frequently  in- 
vades the  tissues  at  a  point  of  least  resistance,  and  produces  either 
a  circumscribed  or  diffused  local  infection.  If  the  organism  gains 
access  to  the  circulatory  system,  from  a  localised  infection,  it  is 
carried  to  various  parts  of  the  body  giving  rise  to  that  type  of  general 
infection  known  as  pyaemia.  In  some  cases  when  the  virulence  of 
the  organism  is  high,  or  the  resistance  of  the  infected  individual  is 
low,  death  may  ensue  within  a  short  time  and  at  autopsy  no  sup- 
purative lesions  (abscesses)  will  be  found,  the  picture  being  that  of  a 
typical  septica;mia.  The  Micrococcus  aureus  is  frequently  as- 
sociated, as  an  important  secondary  invader,  with  lesions  primarily 

'  Annalfs  dc  C'himie  el  Physiologic 
'■'ArctTiv  fur  Klin,  ("hirur.,  ]<S<S<S. 


42  2  THE    ORAL    FLORA 

due  to  some  other  organism,  as  in  processes  originally  caused  by 
the  Bacterium  tuberculosum  or  the  Streptothrix  hovis. 

In  the  oral  cavity  this  organism  is  encountered  as  the  primary 
factor  in  superficial  suppurative  processes:  Phlegmonous  inflamma- 
tion, localised  abscesses,  infections  of  the  salivary  glands,  and  in 
some  cases  of  necrosis;  also  as  a  secondary  invader  in  "pyorrhoea 
alveolaris;"  in  areas  surrounding  infected  teeth;  occasionally  in 
apical  and  alveolar  abscesses;  in  many  cases  of  necrosis  of  the  man- 
dible and  maxillary  bone;  in  tubercular  and  actinomycotic  lesions. 

It  is  the  organism  almost  constantly  found  in  the  peritonsillar 
abscess,  that  condition  known  ordinarily  as  "  quinsy."  Infections  of 
the  nasal  cavity,  antrum  of  Highmore  and  other  accessory  nasal 
sinuses  and  middle-ear  infections,  including  mastoid  disease,  are  not 
infrequently  due  primarily  to  the  action  of  this  organism.  While  the 
Micrococcus  aureus  and  alhus  are  the  most  common  of  the  pyogenic 
organisms,  the  oral  infections  due  to  their  action  constitute  but  a 
very  small  percentage  of  all  infections  of  the  oral  cavity. 

The  toxicity  of  Micrococcus  aureus  is  due  to  an  endotoxin;  which 
endotoxin  or  another  toxic  substance  produced  by  the  organism 
(bacterial  protein  of  Buchner)  exerts  a  positive  chemotactic  action, 
i.e. ,  has  the  property  of  attracting  leucocytes  and  producing  pus.  The 
phlogosine  of  Leber  is  probably  identical  with  this  substance;  it  also 
produces  a  leucocytotoxin  known  as  a  leucocydin.  Some  authors 
claim  that  the  organism  produces  a  soluble  toxin,  but  from  the  fact 
that  this  so-called  soluble  toxin  is  only  found  in  old  cultures,  one  is  led 
to  consider  it  identical  with  the  endotoxin,  being  liberated  by  the 
disintegration  (autolysis)  of  the  bacterial  cells.  The  so-called 
haemolytic  properties  of  this  organism  are  not  due,  as  some  claim,  to 
a  haemolysin,  but  in  all  probability  to  the  proteolytic  enzyme  pro- 
duced by  the  members  of  this  group. 

It  is  of  importance  from  a  dental  point  of  view,  to  note  that  the 
members  of  this  group  produce  enzymes  which  have  the  property 
of  acting  on  lactose,  maltose,  dextrose  and  certain  other  carbo- 
hydrates producing  lactic,  acetic  and  other  mono-carboxylic  fatty 
acids. 

Protective  and  Curative  Inoculations 

Many  attempts  have  been  made  to  produce  an  anti-staphylo- 
coccus  serum.  Several  such  sera,  obtained  by  inoculating  animals 
with  living  and  dead  organisms  and  extracts  of  the  bacterial  cells, 
have  been  highly  lauded  by  the  investigators  whose  experimentation 


ORAL   MICROBIOLOGY  423 

led  to  their  production.  But  it  is  a  pertinent  fact  that  none  of  them 
have  been  employed  to  any  extent  as  therapeutic  measures.  When 
one  states  that  immunity  against  these  organisms  is  essentially 
opsonic  and  agglutinative,  the  reason  for  the  therapeutic  failure  is 
at  once  manifest. 

Bacterial  vaccines,  notably  those  prepared  from  that  strain  of  the 
organism  causing  the  infection,  are  of  great  value  in  treating  and 
preventing  the  recurrence  of  infections  due  to  the  organisms  of  this 
group. 

The  infections  in  which  the  Micrococcus  albus  is  found,  either  as  a 
primary  cause  or  a  secondary  invader,  are  rarely  as  severe  as  those  in 
which  the  Micrococcus  aureus  is  the  causative  agent.  The  action  of 
this  organism  is  of  the  same  nature,  and  due  to  the  same  type  of 
toxic  agents,  as  that  of  the  aureus;  rarely  is  its  virulence  nearly  so 
great  as  that  of  the  latter.  The  albus  is  constantly  found  in  acne 
vulgaris;  frequently  as  a  secondary  invader  of  various  other  condi- 
tions; often  in  association  with  the  aureus. 

One  strain  of  this  organism,  the  Staphylococcus  epidermidis  albus 
of  Welch,  is  found  in  the  superficial  layers  of  the  skin,  notably  in  the 
follicles,  and  has  been  demonstrated  to  be  the  causative  factor  in  a 
large  percentage  of  stitch  abscesses. 

Micrococcus  albus  vaccines  are  of  value  in  treating  localized  infec- 
tions caused  by  this  organism. 

The  third  member  of  this  group,  the  Micrococcus  citreus,  so-called 
from  the  fact  that  in  its  growth  on  artificial  media  a  lemon-yellow 
pigment  is  produced,  is  not  so  commonly  encountered  as  the  aureus 
and  albiis;  some  authors  claim  it  to  be  non-virulent,  while  others 
make  no  mention  of  this  organism  when  deahng  with  the  group. 

The  degree  of  virulence  of  the  citreus  is  as  a  rule  about  the  same  as 
the  albus.  Occasionally  strains  will  be  found  possessed  of  a  very 
high  pathogenicity:  such  strains  have  been  isolated  from  cases  of 
pyaemia  and  carbunculosis.  Citreus  vaccines  are  employed  in 
treating  local  infections  caused  by  this  organism. 

Micrococcus  Catarrhalis. — ^This  organism  is  not  infrequently  found 
in  the  oral  and  nasal  cavities  of  normal  individuals.  It  is  encoun- 
tered in  a  small  percentage  of  all  cases  of  catarrhal  inflammation  of 
the  oral  and  nasal  mucous  membranes;  in  some  instances  it 
has  been  found  in  groups  of  individuals  presenting  catarrhal 
infections;  it  has  also  been  isolated  from  cases  of  bronchitis,  pneu- 
monia, and  other  infections  of  the  mucous  membranes.  The 
I)athogenic  properties  of  this  organism  are  not  marked,  and  its  ac- 


424  THE    ORAL    FLORA 

tion  in  other  than  mild  catarrhal  conditions  is  usually  that  of  a 
secondary  invader,  probably  having  little  to  do  with  the  patho- 
logical process.  The  gingival  trough  is  a  normal  habitat  for  this 
organism.     (See  Vol.  i,  p.  221.) 

In  discharges  from  the  oral  and  nasal  mucous  membranes  the 
organism  appears  as  a  diplococcus,  or  singly  and  in  groups,  in  the 
strands  of  mucus  and  fibrin,  overlying  the  epithelial  cells;  and  not 
infrequently  within  the  protoplasm  of  the  leucocytes.  This  fact  has 
led  to  some  confusion  in  differentiating  this  organism  from  the  Menin- 
gococcus and  Gonococciis,  which  is  inexcusable  in  spite  of  the  fact  that 
they  are  all  Gram  negative,  for  the  cultural  and  biochemical  charac- 
teristics will  readily  enable  one  to  differentiate  between  the  Menin- 
gococcus and  the  Catarrhalis,  and  the  fact  that  the  Gonococciis  will 
only  grow  on  special  media,  renders  the  elimination  of  the  latter 
organism  comparatively  easy. 

The  action  of  the  Micrococcus  catarrhalis  is  apparently  due  to  the 
production  of  an  endotoxin.  Vaccines  have  been  employed  in 
treating  conditions  apparently  due  to  this  organism,  but  the  unusu- 
ally mild  and  acute  character  of  the  infections  make  it  impossible 
for  one  to  determine  whether  or  not  they  are  of  any  value. 

Meningococcus. — This  organism,  discovered  by  Weichselbaum^ 
and  called  the  Diplococcus  intracellular  is  meningitidis,  is  the  cause  of 
the  infection  known  as  epidemic  cerebro-spinal  meningitis.  The 
latter  term  is  in  a  sense  an  unfortunate  one,  as  other  organisms  are 
capable  of  producing  meningitis  of  an  epidemic  character. 

The  organism  is  spherical,  occurring  in  pairs,  usually  within  the 
polymorphonuclear  leucocytes  (pus  cells),  and  is  Gram  negative, 
which  makes  it  imperative  to  exclude  Gonococcus  and  Catarrhalis 
infections  when  making  a  diagnosis.  As  stated  when  considering  the 
Micrococcus  catarrhalis  this  differentiation  should  not  be  difficult. 

The  organisms  gain  access  to  the  tissues  by  way  of  the  oral  and 
nasal  cavities,  and  the  meningeal  symptoms  are  preceded  by  naso- 
pharyngeal symptoms,  which  may  be  manifest  as  a  slight  catarrhal 
disturbance  or  as  a  marked  coryza  and  sore  throat.  An  important 
fact  to  be  noted  is,  that  the  organisms  may  lodge  in  sulci  and  crypts  in 
the  nasal  and  oral  cavities,  notably  in  the  posterior  nares,  of  healthy 
individuals;  the  latter  constituting  the  so-called  carriers,  are  mani- 
festly an  important  factor  in  disseminating  the  disease. 

Gonococcus. — This  organism,  the  Diplococcus  of  Xeisser,  is  the 
cause  of  gonorrhoeal  infection,  usually  affecting  the  urethral  mucous 

^  Grundriss  der  Pathologischen  Histologie. 


ORAL    MICROBIOLOGY  425 

membrane  in  the  male  and  the  vagina  and  urethra  in  the  female. 
The  disease  is  readily  transmissible  to  very  few  species  of  the  lower 
animals.  Infection  of  the  eye,  notably  in  infants  {Ophthalmia 
neonatorum)  is  not  uncommon.  Nasal  and  oral  infections  are,  on 
the  contrary  not  frequently  encountered;  but  when  present  it  is 
manifestly  of  great  importance  that  they  be  recognised. 

The  organism  exerts  a  marked  pyogenic  action  which  becomes 
manifest  as  a  severe  inflammatory  reaction  of  the  mucous  mem- 
branes, accompanied  by  a  profuse  discharge  of  a  purulent  exudate. 
In  this  exudate  the  micrococci  will  be  found  as  diplococci,  usually 
flattened  on  one  side,  within  the  pus  cells.  They  are  Gram  negative, 
which  fact  aids  materially  in  differentiating  them  from  the  ordinary 
pyogenic  cocci.  They  can  be  isolated  only  by  means  of  special 
media,  these  rendering  their  differentiation  from  the  Meningococcus 
and  Catarrhalis  a  matter  of  not  more  than  twenty-four  hours. 

The  Streptococci 

From  a  dental  point  of  view  no  single  species  or  group  of  organ- 
isms, is  of  greater  importance  than  the  streptococci. 

The  older  investigators  divided  the  streptococci  into  the  Strepto- 
coccus longior  et  brevior  or  Streptococcus  longiis  and  brevis,  accord- 
ing to  their  occurrence  in  long  or  short  chains.  The  fact  was  recog- 
nised that  the  organisms  found  grouped  in  long  chains  were  possessed 
of  the  higher  degree  of  virulence.  Among  these  were  classed  the 
Streptococcus  pyogenes,  Streptococcus  erysipelatus,  which  organism  we 
now  recognise  as  not  being  any  different  from  the  pyogenes,  and 
Streptococcus  conglomeratiis,  which  is  simply  a  strain  of  the  pyogenes 
growing  in  conglomerate  masses  of  closely  intertwined  chains.  At 
this  time  that  strain  known  as  Streptococcus  anginosus  was  not  dif- 
ferentiated from  the  pyogenes.  It  is  important  to  note  that  the 
above  types  have  the  property  of  haemolysing  erythrocytes,  which 
fact  has  led  to  their  being  called  the  Hemolytic  streptococci. 

The  .short  chain  streptococci  include  the  organisms  known  as 
Streptococcus  viridans,  Streptococcus  mitis,  Steptococcus  Jcecalis, 
Streptococcus  saliavarius  and  others. 

Some  strains  of  this  latter  group  are  of  great  importance  to  the 
dental  practitioner;  the  most  important,  the  Streptococcus  viridans, 
being  found  in  at  least  go  per  cent,  of  the  oral  cavities  of  human 
beings. 

Some   grouf;    with    the   streptococci   the  Pneumococcus  and  that 


426  THE    ORAL    FLORA 

strain  of  the  organism  known  as  Streptococcus  mucosus  capsulatus. 
From  certain  viewpoints  this  is  of  advantage,  notably  when  making 
isolations  and  group  differentiations. 

Owing  to  the  dental  importance  of  some  members  of  the  group  we 
consider  the  subject  of  sufhcient  importance  to  admit  of  our  discus- 
sing the  group  differentiation  before  taking  up  the  properties  of  the 
various  organisms. 

Streptococci  grouping  and  methods  of  differentiation  have  been 
subjects  of  discussion  and  investigation  for  twenty  years,  the  de- 
tails of  which  will  be  found  in  works  on  the  subject  of  pathological 
bacteriology. 

The  methods  of  differentiation  are  based  principally  upon  the 
morphological  and  biochemical  features.  In  connection  with  the 
former,  such  characteristics  as  the  type  of  chain  formation  and 
whether  or  not  capsules  are  produced;  as  regards  the  latter,  the 
action  on  various  carbohydrates,  on  haemoglobin,  and  the  effect  of 
bile  on  the  life  and  growth  of  the  organism.  Within  the  last  few 
years  differentiation  by  the  complement-fixation  and  agglutination 
reactions  have  aided  in  separating  these  organisms. 

In  discussing  this  phase  of  the  subject,  we  will  assume  that  several 
organisms  have  been  isolated  and  studied  as  regards  their  ordinary 
morphological  characteristics,  cultural  and  biochemical  features.  On 
making  such  studies,  one  is  forcibly  impressed  by  the  marked  simi- 
larity of  the  various  cultures.  One  group  will  not  ferment  lactose: 
the  type  of  this  group  is  Streptococcus  equinus. 

The  next  proceeding  will  be  to  culture  the  organisms  fermenting 
lactose  in  a  medium  (sugar-free  broth  or  serum  water)  containing 
I  per  cent,  of  inulin.  If  the  medium  is  fermented,  the  organism  is 
a  member  of  the  Pneumococcus  group.  This  can  be  confirmed  by 
culturing  in  bile  medium.  The  various  strains  of  the  pneumococcus 
being  bile-soluble,  are  destroyed,  while  the  streptococci  will  develop 
luxuriantly. 

The  organisms  of  the  group  incapable  of  fermenting  inulin  and 
not  bile  soluble,  namely  the  Streptococci,  are  cultured  in  blood-agar 
plates,  when  the  type  of  reaction  admits  of  their  being  separated 
into  three  groups:  (i)  Those  haemolysing  erythrocytes,  which  phe- 
nomenon is  manifest  by  the  appearance  of  a  clear  zone  surrounding 
the  colonies;  these  are  the  Hcemolytic  streptococci;  (2)  Those  pro- 
ducing methgemoglobin,  which  reaction  is  manifest  by  the  appear- 
ance of  a  greenish  colouration  of  the  colony  and  a  greenish  zone  in  the 
medium  immediately  surrounding  it;  this  group  includes  the  Strep- 


ORAL   MICROBIOLOGY  427 

tococcus  viridans  and  the  Streptococcus  salivarius;  (3)  Those  exert- 
ing no  action  on  haemoglobin  or  erythrocytes,  as  the  Streptococcus 
fcBcalis  and  Streptococcus  lactis. 

The  organisms  of  the  hsemolytic  type  may  be  differentiated  by 
culturing  in  a  broth  or  serum- water  medium  containing  the  glucoside 
sahcin;  the  ones  fermenting  sahcin,  with  acid  production  are  strains 
of  the  Streptococcus  pyogenes,  those  not  fermenting  salicin  the  Strep- 
tococcus anginosus. 

Of  the  group  producing  methaemoglobin,  the  Streptococcus  viridans 
ferments  salicin  while  the  Streptococcus  salivarius  does  not.  The 
Streptococcus  fcBcalis,  of  the  indifferent  group,  ferments  the  glucoside 
and  the  Streptococcus  lactis  reacts  negatively. 

Streptococcus  Pyogenes. — This  organism  is  spherical  in  form  and 
found  grouped  in  long  chains.  Such  chains  are  always  manifest  when 
preparations  made  direct  from  pathological  lesions  are  examined,  and 
usually  in  cultures,  especially  when*  cultured  in  liquid  medium  or  in 
the  water  of  condensation  of  blood-serum  or  agar  slants  (Fig.  368). 

This  organism  is  found  as  the  primary  invader  in  a  variety  of 
local  infections,  some  circumscribed,  others  diffuse  as  in  erysipelas, 
and  not  infrequently  as  a  secondary  invader  in  processes  primarily 
due  to  some  other  organism. 

It  is  the  type  usually  found  in  the  septicaemia  following  child- 
birth (puerperal  septicaemia),  in  which  case  the  organism  gaining 
access  to  the  uterus,  by  way  of  the  vagina,  is  absorbed  and  carried 
to  various  parts  of  the  body.  When  this  organism  gains  access  to 
the  general  circulation  from  a  localised  infection  (focal  infection), 
the  resulting  septicaemia  is  generally  of  a  fulminating  character, 
causing  death  within  a  comparatively  short  time;  some  few  cases 
recover.  Cultivation  on  artificial  media  quickly  reduces  the  viru- 
lence of  this  organism.  On  the  other  hand,  the  virulence  may  be 
greatly  enhanced  by  passage  through  animals,  notably  rabbits,  and 
undoubtedly  the  same  increase  in  virulence  is  true  of  organisms 
developing  in  acute  infectious  processes. 

This  organism  is  the  one  usually  concerned  in  follicular  tonsillitis, 
in  some  acute  gingival  and  buccal  infections,  occasionally  in  infec- 
tions of  the  salivary  glands  and  diffuse  cellulitis  of  the  oral  tissues. 
In  a  certain  percentage  of  the  cases  of  that  symptom  complex  known 
as  Ludwig's  angina  the  Streptococcus  pyogenes  is  found;  it  is  en- 
countered in  some  cases  of  necrosis  of  the  mandible  and  maxilla; 
and  aLso  in  a  certain  percentage  of  antral  and  frontal  sinus  infections. 
Contrary  to  the  statements  occasionally  made  to  the  effect  that  this 


428 


THE    ORAL    FLORA 


organism  is  common  in  apical  abscesses,  it  is  but  rarely  found  in 
either  apical  or  alveolar  abscesses.  Neither  is  it  commonly  found 
in  "pyorrhoea  alveolaris." 

This  organism  may  be  the  sole  cause  of  pneumonia  and  not  in- 
frequently secondarily  invades  the  lung  in  cases  of  pneumococcus 
pneumonia.  It  also  frequently  plays  an  important  part  by  secondarily 
invading  a  pulmonary  tubercular  abscess,  in  that  it  adds  to  the  toxae- 
mic  condition  and  induces  the  breaking  down  of  tissue  leading  to 
cavity  formation. 

The  toxic  products  of  the  organism  are,  an  endotoxin,  a  soluble 
toxin,  and  a  hasmolysin. 


Fig.  368. — Streptococcus  longiis  {pyogenes),  from  a  fatal  case  of  pvEemia. 
nified  1,000  times.      {Trans.  Odonto.  Soc.  of  Great  Britain.)    i 


Mag- 


Anti-streptococcus  sera  of  various  types  have  been  employed  in 
treating  different  types  of  streptococcus  infection.  On  the  whole  the 
results  have  been  extremely  disappointing.  Autogenous  strepto- 
coccus vaccines  are  of  value  in  treating  certain  acute  and  subacute 
infections.  They  may  be  employed  in  general  infections,  but  the 
results  obtained  are  not  of  such  a  nature  as  to  cause  one  to  consider 
them  among  the  important  therapeutic  measures.  The  so-called 
stock  polyvalent  streptococcus  vaccines  are,  in  the  writer's  opinion, 
of  absolutely  no  value. 

Streptococcus  anginosus. — This  organism  is  closely  related  to  the 
Streptococcus  pyogenes,  occurring  in  the  same  long  chains,  exerting 
a  haemolytic  action,  but  differing  from  it  in  the  fact  that  salicin  is 


ORAL    MICROBIOLOGY 


429 


not  fermented.     As  a  rule  it  causes  coagulation  in  milk.     The  latter 
feature  however  is  not  constant. 

This  strain  is  found  in  a  large  percentage  of  cases  of  so-called  epi- 
demic septic  sore  throat,  and  is  also  encountered  as  a  secondary 
invader  in  many  cases  of  scarlet  fever.  Extensive  epidemics  of 
septic  sore  throat  have  been  reported  from  time  to  time  in  various 
countries,  and  in  America  numerous  epidemics  have  occurred. 
This  type  of  sore  throat,  affecting  the  fauces  and  tonsils,  is  very 
severe  and  accompanied  by  marked  constitutional  symptoms,  at 
times  due  to  toxaemia.  In  other  cases,  in  addition  to  this,  the  organism 
invades   the   tissues   via   the   circulation,  producing   a   septic£emia 


Fig.  369. — SLreplococcus  brevis,  from  a  healthy  mouth.      Magnified  1,000  times. 
(Trans.  Odonto.  Soc.  of  Great  Britain.) 


which  has  resulted  in  a  comparatively  high  percentage  of  deaths. 
The  organism  giving  rise  to  the  epidemic  may  be  disseminated  by 
means  of  milk  from  cows  affected  with  mastitis;  or  by  individuals 
who  are  infected  with  the  organism  handling  the  milk,  or  receptacles 
in  which  it  is  collected  and  distributed;  in  other  epidemics  the  organ- 
isms are  evidently  disseminated  in  some  other  manner. 

Vaccines  and  sera  are  of  little  or  no  value  in  treating  this  infection. 

Streptococcus  Viridans. — This  name  is  applied  to  that  short  chain 
streptococcus  producing  methaemoglobin  when  cultured  in  blood 
media,  and  fermenting  salicin  with  acid  formation. 

This  organism  is  constantly  encountered  in  the  oral  cavity,  not 


430  THE    ORAL    FLORA 

only  in  pathological  conditions  but  also  in  healthy  individuals,  even 
of  those  who  exercise  great  care  in  cleansing  their  mouths  (Fig.  369). 

It  is  encountered  as  the  primary  cause  or  as  a  secondary  invader 
in  the  majority  of  oral  infections,  in  fact  in  practically  all  superficial 
infections.  In  some  cases  its  presence  is  of  no  moment,  in  others  it 
has  a  marked  detrimental  action  on  the  tissues.  The  presence  of 
this  organism  in  apical  abscesses  is  almost  constant,  and  it  is  found 
in  a  great  percentage  of  alveolar  abscesses.  In  many  cases  of  antral 
and  frontal  sinus  infections  the  viridans  is  encountered  either  alone 
or  in  association  with  some  other  organism.  Manifestly  it  is 
present  in  many  cases  of  necrosis. 

When  this  organism  gains  access  to  the  circulation  from  a  focal, 
infection  it  is  carried  to  all  parts  of  the  body.  It  rarely  possesses  a 
marked  degree  of  virulence  and  therefore  does  not  often  give  rise 
to  a  fulminating,  but  rather  to  a  low-grade  septicaemia.  In  many 
cases  when  it  is  disseminated  throughout  the  body,  the  pathological 
action  is  not  manifest  as  a  general  infection  but  localised  in  one  part, 
and  such  conditions  as  arthritis,  synovitis,  neuritis,  endocarditis,  etc., 
arise.  Very  often  clearing  up  of  the  focal  infections  leads  to 
the  disappearance  of  all  symptoms.  The  reason  for  this  is  mani- 
fest; the  organism  possesses  a  low  degree  of  virulence  and  the  bodily 
defenses  are  enabled  to  prevent  a  general  action  on  the  tissues. 
Many  of  the  organisms  are  destroyed;  those  remaining  in  a  locality 
of  lowered  resistance  are  enabled  to  develop  and  exert  a  detrimental 
action  on  the  tissues.  In  many  cases  when  these  organisms  produce 
a  low-grade  septicaemia,  the  condition  may  be  cured  or  may  lead  to 
the  death  of  the  patient  after  a  somewhat  prolonged  illness. 

Streptococcus  Salivarius. — This  strain  of  the  short  chain  strepto- 
cocci may  be  encountered  in  the  same  type  of  infection  as  the 
viridans;  it  is  however,  as  a  rule  possessed  of  but  a  very  low  degree 
of  pathogenicity. 

Pneumococcus  or  Diplococcus  PneumonicB. — This  organism  in  cul- 
tures cannot  always  be  differentiated  readily  from  the  short  chain 
streptococci,  as  it  frequently  occurs  in  short  chains  and  reacts 
culturally  in  about  the  same  manner.  The  various  types  of  this 
organism  ferment  lactose  and  inuHn:  all  are  bile  soluble.  Within  the 
last  few  years  various  types  have  been  separated;  types  differing  one 
from  the  other  sufficiently  to  admit  of  their  being  differentiated 
biologically;  pathologically  their  action  is  much  the  same.  For 
information  on  this  and  the  general  phases  of  pneumococcus  infec- 


ORAL    MICROBIOLOGY  43 1 

tion,   the   student   is    referred    to    recent    works    on   pathological 
bacteriology. 

When  stained  by  appropriate  methods  in  sputum,  catarrhal 
exudates,  pus,  blood  and  tissue  fluids,  the  organism  appears  as  a 
diplococcus  surrounded  by  a  definite  capsule.  At  times  three  or 
four  elements  will  be  enclosed  in  one  capsule;  one  type  called  the 
Streptococcus  mucosus  capsulatus  occurs  in  long  chains  surrounded  by 
a  distinct  capsule. 

The  Pneiimococcus  is  not  infrequently  found  in  the  oral  cavities 
of  healthy  individuals;  therefore  one  might  expect  to  find  it  in  vari- 
ous pathological  conditions.  In  some  cases  of  ulcerative  stomatitis, 
in  which  there  are  present  small,  often  painful,  superficial  ulcers,  the 
pneumococcus  is  present  as  the  primary  infective  agent;  it  is  found 
in  many  cases  of  "pyorrhoea"  and  other  gingival  infections.  If  alveo- 
lar abscesses  be  detected  soon  after  their  formation  and  proper  pre- 
cautions be  taken  in  opening  and  examining  their  contents,  the 
pneumococcus  will  be  frequently  found  in  pure  culture;  it  is  however, 
rarely  found  in  apical  abscesses.  Occasionally  the  pneumococcus  in 
association  with  streptococci  and  other  organisms,  is  encountered  in 
necrosis.  Not  infrequently  it  is  found  in  antral  infections.  Should 
the  organism  gain  entrance  to  the  general  circulation,  a  pneumococcus 
septicaemia  may  result.  There  are  on  record  cases  of  pneumococcus 
meningitis;  in  some  of  these  cases  the  organisms  in  all  probability 
gain  access  to  the  cranial  cavity  by  way  of  the  nose  or  naso-pharynx. 

This  organism  has  been  demonstrated  in  not  a  few  cases  of  acute 
catarrhal  infection  of  the  upper  air  passages  as  apparently  the  only 
organism  present  capable  of  causing  such  infection.  Pneumococcus 
conjunctivitis  is  a  well-recognised  infection. 

Bacillus  diphtherics,  or  more  properly  speaking.  Bacterium  or 
Mycobacterium  diphtheriticum,  the  cause  of  the  disease  known  as 
diphtheria,  is  occasionally  encountered  in  infections  of  the  oral 
mucous  membrane.  The  fact  that  such  infections  are  not  more 
common  is  somewhat  surprising  when  one  considers  the  frequency 
of  diphtheritic  infection  of  the  tonsils  and  pharynx. 

This  organism  occurs  in  the  form  of  short  or  long  rods  presenting 
clavate  or  cuneate  swellings.  In  stained  preparations  the  proto- 
plasm, instead  of  appearing  homogeneous  or  finely  granular,  is 
barred  or  striated,  in  many  cases  containing  metachromatic  granules 
which,  when  stained  by  appropriate  methods,  assume  a  colour 
different  from  the  other  constituents  of  the  cell,  indicating  that  chem- 
ically they  are  of  a  different  nature  from  the  rest  of  the  protoplasm. 


432  THE    ORAL    FLORA 

When  a  given  strain  of  this  organism  is  cultivated  on  various  kinds  of 
media  and  examined,  one  is  forcibly  impressed  with  the  marked 
variations  in  morphology  exhibited;  variations  in  the  reaction  of  the 
medium:  presence  of  substances  exerting  a  detrimental  action  on  the 
organism.  Hypo-  or  hypertonicity  seem  to  be  the  determining  factors 
in  these  morphological  variations.  The  bizarre  forms  are  known  as 
involution  forms;  under  certain  conditions  of  cultivation  the  organ- 
isms present  buds  and  not  infrequently  short  and  long  branches 
which  branches  are  frequently  swollen  at  the  ends. 

The  pathogenic  action  of  the  organism  is  due  solely  to  a  soluble 
toxin;  as  a  means  of  combating  diphtheritic  infection  an  antitoxic 
serum  is  employed. 

From  a  dental  viewpoint  it  is  of  importance  to  note  that  healthy 
individuals  may  be  carriers,  the  organism  developing  in  the  crypts 
of  the  tonsils  and  sulci  in  the  naso-pharynx. 

There  are  several  types  of  organisms  morphologically  like  the 
Mycobacterium  diphtheriticum,  which  are  frequently  encountered  in 
the  oral  cavity,  some  colourless,  others  producing  coloured  growths  on 
artificial  media.  These  are  grouped  under  the  general  term  of  pseudo- 
diphtheritic  organisms.  Pathologically  from  our  viewpoint  they  are  of 
very  little  import.  Some  strains  may  be  concerned  in  mild  catarrhal 
conditions  of  the  oral  and  nasal  mucous  membranes.  The  chromo- 
genic  types  are  commonly  found  in  milk. 

The  import  of  this  group  rests  on  the  fact  that  they  resemble  the 
diphtheria  organism  morphologically,  and,  to  a  great  extent,  cul- 
turally, and  must  be  differentiated  from  the  latter  in  suspicious  cases. 
In  no  case  do  they  induce  infection  in  any  manner  resembling 
diphtheria. 

Bacillus  tuber cidosis,  or  Mycobacterium  tuberculosis,  is  the  cause  of 
the  various  tubercular  infections  as:  pulmonary  tuberculosis,  general 
miliary  tuberculosis,  glandular  tuberculosis,  tuberculosis  of  the 
skin,  etc.  This  organism  is  one  of  the  few  that  can  be  readily  and 
positively  diagnosed  in  stained  preparations  of  sputum,  pus,  etc., 
the  diagnosis  depending  on  the  fact  that  one  of  the  constituents  of 
the  cell  of  the  organism  is  a  peculiar  wax  which  gives  to  it  "acid-fast" 
or  acid-resisting  properties.  It  stains  with  difficulty,  but  when  once 
stained,  retains  the  stain  tenaciously,  resisting  to  a  marked  degree  the 
action  of  decolourising  agents.  Therefore  when  material  is  stained 
with  an  intense  red  dye  such  as  carbo-fuchsin;  treated  with  decolour- 
ising agents  such  as  30  per  cent,  nitric  acid,  5  per  cent,  sulphuric  acid 
or  acid  alcohol;  washed  and  counter-stained  with  methylene  blue,  the 


ORAL   MICROBIOLOGY  433 

presence  of  the  B.  tuberculosis  is  indicated  by  the  finding  of  red  rods, 
straight  or  curved,  usually  beaded,  in  a  field,  all  other  elements  of 
which  are  stained  blue. 

Tubercular  infections  are  of  great  importance  to  the  dental  prac- 
titioner. In  the  first  place  in  pulmonary  tuberculosis  the  organisms 
are  present  in  the  sputum,  and  manifestly  in  the  oral  cavity.  Tuber- 
cular infections  of  the  tonsils  and  oral  mucous  membrane  are  not 
common  but  are  occasionally  encountered.  (See  page  355) .  Tuber- 
cular infection  of  the  salivary  glands  are  occasionally  seen,  as  is  tuber- 
cular caries  of  the  mandible  and  tubercular  antral  infections.  One 
type  of  tubercular  infection,  the  lesions  of  which  are  not  infrequently 
mistaken  by  the  dentist  as  being  due  to  syphilitic  infection,  is  that 
condition  of  the  nose  and  face  commonly  known  as  Lupus  vulgaris. 
Not  infrequently  this  results  in  a  destruction  of  tissue  to  such  an 
extent  as  to  cause  marked  disfigurement,  not  only  by  destroying  the 
soft  tissue  of  the  nose  but  bony  tissue  as  well.  In  all  of  these  con- 
ditions the  organism  may  be  readily  demonstrated  in  the  tissue  by 
appropriate  methods  of  staining. 

Bacillus  Mallei,  Glanders  Bacillus,  or  Mycobacterium  Mallei,  is  the 
causative  agent  in  the  disease  known  as  glanders.  This  disease  is 
primarily  a  disease  of  horses,  mules  and  asses,  but  is  occasionally 
transmitted  to  other  domestic  animals  and  man.  There  has  been 
much  discussion  as  to  the  portal  of  entrance  of  the  organism,  but 
undoubtedly  in  a  certain  percentage  of  cases,  it  gains  access  by  way  of 
the  nasal  and  oral  orifices. 

Veterinarians,  hostlers  and  others  coming  in  contact  with  horses 
are  most  often  infected,  and  present  oral  and  nasal  inflammatory 
lesions  due  to  the  action  of  this  organism. 

Bacillus  anthracis  or  Bacterium  anthracis  is  a  rod-shaped  organism, 
non-motile,  occurring  in  chains  and  forming  endospores.  It  is  the 
causative  agent  in  the  disease  known  as  Anthrax,  Charbon,  or  Malig- 
nant pustule.  This  infection,  primarily  a  disease  of  cattle  and  sheep, 
may  be  transmitted  to  man.  The  organism  enters  the  tissue  through 
an  abrasion,  or  by  way  of  the  nasal  and  oral  cavities,  being  taken  into 
the  lungs  with  dust,  and  into  the  intestinal  tract  with  food  and 
drink.  It  produces  a  marked  oedematous  inflammation  at  the 
point  of  entrance,  and  fulminating  septicaemia  when,  after  gaining 
access  to  the  circulation,  the  organisms  are  carried  to  all  parts 
of  the  body.  The  pulmonary  type  of  anthrax  infection  is  fre- ' 
quently  called  "  wool-sorter's  disease." 

Bacillus  mucosus  capsulalus,  Friedldnder' s  bacillus,  or   the  Bac- 
28 


434  THE    ORAL    FLORA 

terium  mucosum  capsiilahim  is  a  capsulated,  non-motile,  rod-shaped 
organism  which  does  not  form  endospores. 

Classed  under  this  group  are  several  types  varying  not  at  all 
morphologically  and  but  very  little  culturally.  They  are  differen- 
tiated one  from  the  other  essentially  by  their  action  on  certain  carbo- 
hydrates. One  type,  the  B.  rhino scleromatus,  is  found  in  the 
disease  known  as  rhinoscleroma;  a  second,  the  B.  oezencB,  occurs  quite 
constantly  in  cases  of  foetid  catarrhal  inflammation  of  the  nose. 
The  Bacterium  mucosum  capsulatum  is  very  frequently  encountered 
in  the  oral  cavities  of  healthy  individuals;  it  exists  also  in  a  variety 
of  pathological  conditions,  probably  rarely  as  a  primary  cause, 
but  rather  as  secondary  invader.  Some  claim  that  this  organism  is 
the  cause  of  scleroma  Ungues. 

Bacillus  aerogenes  capsulatus,  the  so-called  gas  bacillus  of  Welch 
is  found  in  the  intestinal  tract  of  man  and  lower  animals.  This 
organism  is  the  cause  of  gas  gangrene,  the  gas  production  being  due 
to  its  ability  to  split  up  complex  substances,  notably  carbohydrates, 
with  the  formation  of  simpler  compounds,  among  which  are  certain 
gases. 

This  same  organism  has  been  described  by  various  authors  who 
apparently  knew  nothing  of  the  work  of  Welch.  The  Bacillus  per- 
fringens,  the  Bacillus  of  GJion  and  Sachs,  Bacillus  phlegmonous 
emphysematosce  of  Fraenkel  and  others  are  identical  with  the  bacillus 
of  Welch. 

This  organism  is  a  strict  anaerobe,  occurs  singly  and  in  chains. 
When  found  in  the  tissues  and  stained  appropriately,  it  always  pre- 
sents a  distinct  capsule.  It  is  non-motile,  forms  endospores  and 
reacts  positively  to  Gram's  stain.  Its  natural  habitat  is  evidently 
the  soil.  This  organism  has  been  encountered  not  only  in  the  oral 
cavities  of  normal  individuals,  but  in  pathological  conditions  where 
individuals  have  extensive  injuries  to  the  face  and  oral  tissues, 
notably  when  soil  and  excrementitious  substances  contaminate  the 
wounds.  The  danger  of  such  infection  should  be  realized  and 
proper  precautions  taken  against  such  untoward  complications 
occurring. 

It  has  been  claimed  that  Miller  first  discovered  this  organism  as 
existing  in  the  oral  cavity. 

Bacillus  Tetani. — This  organism,  a  strictly  anaerobic,  spore-form- 
ing motile  rod,  is  the  cause  of  the  disease  known  as  tetanus,  fre- 
quently called  "lockjaw." 

While  tetanic  spasm  of  the  jaws  is  a  prominent  symptom  of  this 


ORAL    MICROBIOLOGY 


435 


disease  it  is  rare  to  find  the  focus  of  invasion  in  the  oral  cavity,  al- 
though the  organism  is  undoubtedly  frequently  present  here  as 
well  as  in  the  intestinal  tract  of  healthy  individuals. 

This  organism  is  constantly  encountered  in  the  soil  in  some  loca- 
hties,  and  gains  access  to  the  tissues  through  wounds,  developing  at 
the  point  of  invasion,  producing  a  soluble  toxin  which  is  carried 
throughout  the  tissues  by  the  circulation,  the  organism  remaining 
at  the  local  lesion. 

There  are  other  anaerobic  organisms  found  in  the  soil  which  may 
be  found  in  the  oral  cavity.     Some  are  pathogenic  but,  rarely,  if 


Fig.  370. — Slreplolhrix  aUinomyces.  From  section  of  a  tongue  of  an  ox. 
Stained  by  Gram's  method,  counterstained  with  eosine.  Magnified  800  times. 
C.    Club-shaped  forms. 


ever,  concerned  in  oral  infections.  Some  are  organisms  of  the 
malignant  oedema  type,  others,  while  not  of  a  pathogenic  nature, 
may  play  an  important  role  in  dental  caries. 

Streptothrix  bovis,  variously  known  as  Streptothrix  actinomyces, 
Actinomyces  bovis,  Discomyccs  bovis,  the  Ray  fungus,  occurs  as  long 
thread-like,  interlacing  filaments,  presenting  a  true  branching  and  at 
times,  small  spherical  bodies,  the  true  significance  of  which  is  still 
a  mooted  question,  some  writers  claiming  they  arc  spores  or  conidia 
and  others  denying  this. 


436 


THE    OEAL    FLORA 


Pig.  371. — The  same.     From  a  culture.      Magnified  800  times. 


Fig.  372. — Cladothrix  dichotoma.     Stained  by  Gram's  method.      Magnified  800 

times. 


ORAL    MICROBIOLOGY 


437 


When  examining  pus,  sputum,  and  the  tissues  of  infected  animals, 
small  yellowish  or  whitish  opaque  granules  will  be  found,  usually 
about  the  size  of  a  millet  seed.  If  these  granules  are  crushed, 
stained  and  examined  microscopically,  the  organism  will  be  readily 
demonstrated  as  long  entangled  branched  filaments,  usually  termi- 
nating in  bulbous  ends  (clubbed).  These  filaments  in  general 
arrangement  radiating  from  the  centre  give  rise  to  a  radiate  mass 
which  led  to  the  organism  being  called  the  'S-ay  fungus."  In 
tissue  sections  the  radiate  colonies  are  readily  demonstrated. 

This  organism  is  the  cause  of  "lump-jaw"  and  "  wooden  tongue" 
or  actinomycosis  of  cattle,  but  while  it  is  frequently  localised  in  the 


Fig.  373- — Cladothrix  from  mouth  direct.     Stained  by  Gram's  method, 
nified  1,000  times.      {Trans.  Odonto.  Soc.  of  Great  Britain.) 


Mag- 


mandible,  the  organism  in  many  cases  invades  the  other  tissues. 
In  man,  oral  actinomycosis  is  occasionally  encountered,  not  only 
as  lesions  of  the  mandible  and  maxilla,  but  the  soft  tissues  as  well, 
notably  the  tongue. 

The  name  Streptolhrix  hominis  has  been  given  to  some  organisms 
of  this  group  from  human  sources.  Whether  or  not  this  is  a  type 
different  from  the  bovis  is  an  open  question.  One  type  found  not 
infrequently  in  the  oral  cavity  has  been  named  the  Slreptothrix  buc- 
calis.  This  organism  is  encountered  in  apparently  healthy  indi- 
viduals, usually  those  whose  mouths  arc  not  kept  clean.  It  has 
been  encountered  in  the  tonsillar  crypts,  in  the  so-called  mycosis  of 
the  tonsils;  and  in  deep  tonsillar  lesions.     Similar  organisms  have 


438  THE    ORAL    FLORA 

been  found  in  a  few  of  those  cases  of  chronic  bronchitis  in  which 
there  is  a  very  profuse  expectoration  of  a  muco-purulent  material 
(bronchorrhoea). 

Members  of  the  streptothrix  group  have  frequently  been  mistaken 
for  the  Cladothrix  dichotoma,  an  organism  belonging  to  the  genus 
Cladothrix  or  Sphcerotilus  of  the  family  of  ChlamydobacteriacecB. 
Their  cultural  characteristics  are  similar;  but  by  appropriate 
methods  of  staining,  the  latter  organism  will  be  found  to  present 
a  distinct  sheath  and  the  apparent  branching  to  be  not  a  true, 
but  a  false  branching.  This  organism  is  occasionally  found  in  the 
oral|cavity_but  is  of  no  pathological  significance  (Fig.  373). 


Fig.  374. — Cladothrix.     Forty-eight  hours'   cultivation  in  agar.      Magnified  500 
times.      {Trans.  Odonlo.  Soc.  of  Great  Britain.) 

Bacillus  fusiformis  or  Mycobacterium  fusiformi  was  first  dis- 
covered by  Vincent  in  cases  of  hospital  gangrene.  This  organism 
is  almost  invariably  associated  in  pathological  conditions  with  the 
Spirochceta  vincenti  (Treponema  vincenti).  Both  are  anaerobic 
organisms  and  are  difficult  to  isolate,  but  may  be  readily  demon- 
strated in  the  exudate- from  pathological  conditions  in  which  they 
are  present,  making  a  diagnosis  not  difficult.  Some  claim  that  they 
are  but  pleomorphic  forms  of  one  organism.  This  view,  however,  can- 
not be  accepted.  The  Bacillus  fusiformis  is  a  non-motile,  rod-shaped 
organism,  slightly  enlarged  in  the  middle  and  pointed  at  the  ends. 
The  Treponema  vincenti  is  a  long  slender,  curved,  wavy  or  sinuous 
organism  somewhat  thickened  at  the  middle  and  gradually  taper- 


ORAL    MICROBIOLOGY 


439 


ing  out  to  a  thin  flagella-like  filament  at  the  ends.  When  examined 
under  dark  field  illumination  the  organism  will  be  found  to  present 
active  sinuous  and  wavy  movements. 

These  organisms  are  constantly  found  in  that  tonsillar  infection 
known  as  Vincent's  angina;  in  certain  types  of  locahsed  and  spreading 
vilcerative  stomatitis  (especially  along  the  gingival  border) ;  in  many 
cases  of  "pyorrhoea  alveolaris;"  in  some  cases  of  that  diffuse  cellulitis 
of  the  floor  of  the  mouth,  frequently  called  Ludwig's  angina  (Angina 
Ludovici);  occasionally  in  infections  of  the  salivary  glands,  notably 
the  submaxillary  and  sublingual;  constantly  in  gangrenous  stoma- 
titis or  noma  (Cancrum  oris).  The  infection  called  "  trench  mouth  " 
is  an  ulcerative  stomatitis,  the  causative  agents  of  which  are  the 
Bacillus  fusiformis  and  the  Treponema  vincenti.  Infections  due  to 
these  organisms  occur  in  various  other  parts  of  the  body. 

Spiroch(Bta  pallida  or  Treponema  pallidum,  the  specific  infective 
agent  of  syphilis,  will  be  found  in  the  primary  and  secondary  oral 
lesions  of  syphihs,  when  material  from  the  lesions,  carefully  obtained, 
is  examined  by  dark  field  illumination  or  in  preparations  stained  by 
special  methods. 

Under  dark  field  illumination  it  is  seen  as  a  spirally  curved  organ- 
ism turning  rapidly  upon  itself  and  presenting  a  rotary  and  sinuous 
movement. 

When  stained  by  appropriate  methods  the  organism  appears  as 
spiral  cells  from  8  to  14  //  in  length,  tapering  tp  a  slender  flagella- 
like  extremity  at  each  end.  The  turns  of  the  spiral  are  close  and 
regular.  It  cannot  be  demonstrated  by  the  ordinary  methods  of  stain- 
ing; other  spiroch£etes  have  been  mistaken  for  the  pallida,  but  the 
danger  of  one  who  has  had  some  experience  of  making  such  an  error  is 
slight,  the  other  types  varying  in  size,  form  and  arrangement  of  the 
spirals  to  such  an  extent  as  to  render  their  elimination  an  easy ' 
matter.  Several  spirochgetes  have  been  described  as  frequently 
occurring  in  the  mouth,  one  author,  basing  his  contention  on  morpho- 
logical grounds  alone,  separated  them  into  eight  species.  This  is  un- 
doubtedly erroneous.  The  Treponema  microdentium,  formerly  called 
Spiroch(Ete  dentium,  and  the  Treponema  macrodentium,  formerly 
called  the  Spirochcele  buccalis  and  the  Treponema  vincenti  are  the 
ones  most  commonly  found.  They  are  readily  demonstrated  in 
stained  preparations. 

Oidium   Albicans— Saccharomyces   Albicans   or   Endomyces   Albi- 
cans.—TYns  organism  belongs  to  the  same  group  of  cryptogams  as 


440 


THE    ORAL    FLORA 


the  yeasts,  namely  the  Eumycetes  or  true  fungi,  order  of  Asco- 
mycetes.     The  oidium  evidently  belongs  to  the  family  Endomyces. 

This  organism  is  the  cause  of  mycotic  stomatitis,  the  condition 
variously  known  as  "thrush."  Some  have  called  the  condition 
oidiomycosis,  rather  unfortunately,  as  this  name  has  also  been 
applied  to  blastomycotic  dermatitis. 

If  a  small  particle  of  one  of  the  characteristic  milk  white,  friable 
patches  from  the  oral  mucous  membrane  be  spread  upon  a  slide, 
stained  and  examined,  long  filaments,  septated  into  oval  or  rod- 
shaped  elements,  will  be  found.  There  are  frequently  present  numer- 
ous spherical  or  oval  bodies,  often  containing  a  smaller  spherical 
body,  known  as  the  ascospore. 


Fig.   375. — Oidium  albicans.     From  a  culture.      Magnified  600  times. 


Several  kinds  of  Yeasts  have  been  encountered  in  oral  infections. 
Whether  or  not  they  are  distinct  types  is  a  question,  as  the  descrip- 
tions given  are  not  sufficiently  complete  to  admit  of  absolute  differ-, 
entiation.  From  the  similarity  of  the  lesions  produced,  the  majority 
are  undoubtedly  identical  with  the  Blastomyces  dermatidis  of  Gil- 
christ, first  found  in  a  peculiar  type  of  chronic  dermatitis.  This 
organism  is  occasionally  encountered  in  a  chronic  ulcero-granulo- 
matous  condition  of  the  oral  tissues,  which  has  in  some  cases 
been  mistaken  for  carcinoma  until  a  microscopic  examination  cleared 
up  the  diagnosis.  In  the  tissues  the  organism  appears  as  oval  or 
spherical    cells,    averaging    from    10    to    12    fx    in    diameter;    the 


ORAL    MICROBIOLOGY  441 

majority  of  the  cells  being  about  5  yu  in  diameter,  while  some 
elements  are  much  larger. 

The  cell,  by  appropriate  methods  of  staining,  presents  a  thick 
membrane  surrounding  the  central  protoplasm.  These  cells  not  in- 
frequently, owing  to  the  fact  that  they  multiply  by  budding  at  least 
in  one  stage  of  their  development,  occur  in  pairs  of  unequal  size. 

A  Yeast,  the  Saccharomyces  nigrans,  has  been  found  in  some  cases 
of  Linguce  nigra  or  black  tongue.  When  examined  microscopically 
the  cells  appear  as  small  oval  bodies,  occurring  singly  and  in  pairs. 
Occasionally  three  will  be  grouped  together;  one  cell,  the  parent  cell, 
will  be  larger,  the  attached  cells  smaller  than  those  occurring  singly. 
In  cultures  this  organism  produces  a  black  pigment.  The  organism 
commonly  found  in  the  mycotic  type  of  Linguce  nigra  is  however  not 
a  yeast  but  the  Rhozopus  nigrans,  a  black  mould  closely  related  to, 
some  claim  identical  with,  the  Mucor  nigrans.  In  stained  prepara- 
tions this  organism  may  be  demonstrated  among  the  epithelial 
cells  as  long  filaments  septate  and  often  branched.  At  times  the 
characteristic  oval  or  round  spores  will  be  found  in  such  preparations. 

Sporothrix  Infections. — The  organisms  causing  the  so-called 
Sporothricosis  apparently  belong  to  the  Ascomycetacea;  the  type 
organism  is  the  Sporothrix  schencki.  This  organism  invades  the 
tissues  at  some  local  point,  usually  where  their  resistance  has 
been  lowered,  and  gives  rise  to  peculiar  hard,  indurated  sub- 
cutaneous and  submucous  lesions  in  man.  These  lesions  frequently 
break  down  and  abscesses  are  formed  which  are  usually  chronic. 
The  organism  may  invade  the  buccal,  pharyngeal  and  laryngeal 
mucous  membranes.  In  the  purulent  exudate  the  organism  is 
found  among  the  pus  cells  as  yeast-like  cells,  oval  and  fusiform  in 
character;  at  times  a  filament  will  be  found  with  groups  of  the  oval 
bodies  (spores)  arranged  about  the  end.  The  organism  is  readily 
isolated  and  cultivated  on  artificial  media.  In  such  cultures  the 
morphological  characteristics  of  the  organism  vary  quite  markedly 
from  the  characteristics  of  the  organism  as  found  in  the  tissues. 

THE   FILTERABLE  VIRUSES 

There  are  certain  diseases  having  all  the  characteristics  of  infec- 
tions, in  which  all  attempts  made  at  isolating  the  causative  agents 
or  even  demonstrating  such  agents  microscopically,  have  met  with 
failure.  Further  investigation  demonstrated  the  fact  that  when 
the  material,  macerated  and  diluted,  was  passed  through  a  so-called 


442  THE    ORAL    FLORA 

germ-proof  filter,  the  filtrate  when  injected  into  suitable  animals 
gave  rise  to  the  same  type  of  infection  as  that  in  which  the  original 
material  was  found.  Several  such  infections  exist,  of  which  the  one 
of  most  importance  to  the  dentist  is  ''foot-and-mouth  disease,"  or 
aphthous  fever.  While  primarily  a  disease  of  cattle,  sheep,  goats, 
and  pigs,  the  infective  agent,  during  epidemics,  not  infrequently 
gains  access  to  the  oral  cavities  of  human  beings  directly  from  in- 
fected animals,  infected  milk,  etc.,  and  causes  a  severe  aphthous 
inflammation. 

Endamceba  Gingivalis  (Gros). — This  protozoon  was  first  described 
by  Gros  in  1849,  and  named  Amoeba  gingivalis;  since  then  it  has 
been  observed  by  others  and  variously  named  Amoeba  buccalis, 
Amoeba  dentalis  and  Entamoeba  buccalis  (Fig.  376). 

The  organism  was  frequently  observed  in  microscopic  preparations 
from  dirty  mouths,  pyorrhoeal  infections,  etc.  However  no  patholog- 
ical significance  was  attached  to  its  presence  until  Smith  and  Barrett,^ 
after  a  study  of  a  group  of  cases  of  "Pyorrhoea  alveolaris,"  announced 
the  fact  that  the  organism  was  found  in  a  large  percentage  of  cases  of 
infected  gingival  tissues.  They  ascribed  to  it  an  important  etiolo- 
gical relationship  as  regards  pyorrhoeal  infections. 

The  organism  may  be  demonstrated  in  fresh  preparations  by  mix- 
ing the  material  with  a  drop  of  salt  solution  on  a  warm  sHde,  applying 
a  cover  glass  and  searching  the  slide  for  motile  organisms  with  an 
8-mm.  lens.  The  preparation  must  be  kept  warm,  therefore  the 
search  is  best  made  with  a  microscope  fitted  with  a  warm  stage. 

The  organism  may  also  be  readily  demonstrated  in  dried  prepara- 
tions by  staining  with  appropriate  stains,  as  Giemsa's  method  or 
with  carbol-fuchsin  followed  by  methylene-blue. 

In  fresh  preparations  the  Endamoebce,  averaging  about  30  yu  in 
diameter  are  quite  actively  motile,  presenting  an  irregular  outline, 
due  to  throwing  out  of  pseudopodia.  In  the  quiescent  stage  they  are 
usually  circular  or  oval,  the  ectoplasm  is  hyaline,  while  the  endo- 
plasm  is  granular  and  usually  contains  bacteria,  disintegrated  ery- 
throcytes and  leucocytes.  The  nucleus  can  rarely  be  seen  in  fresh 
preparations.  Vacuoles  are  usually  present,  some  empty  while  others 
contain  inclusions  of  different  sizes  and  shapes.  When  stained, 
the  ectoplasm  usually  appears  to  be  finely  granular  in  structure;  the 
endoplasm  coarsely  granular  and  frequently  alveolated.  Inclusions 
of  various  sizes  and  shapes  are  usually  found  within  the  endoplasm. 

^"The  Protozoa  of  the  Mouth  in  Relation  to  Pyorrhcea  Alveolaris,"  "Dental 
Cosmos,"  Aug.,  1914. 


ORAL    MICROBIOLOGY 


443 


The  nucleus  is  circular  or  oval  with  a  centrally  located  chromatin 
mass. 

ADVENTITIOUS    BACTERIA    OF    MOUTH 

There  are  other  organisms  found  in  material  from  the  mouth  which 
have  not  been  encountered  in  any  other  place,  although  their  original 
habitat  is  undoubtedly  some  place  in  nature,  as  soil,  water,  etc. 
Certain  of  these  organisms  are  bacteria,  others  higher  fungi;  they 


Pig.  376. — Endamoeba  gingivalis.     a.   AmceljcP;   l.  Polymorphonuclear  leucocyte. 
{Photomicrograph  by  courtesy  of  Dr.  Percy  R.  Howe.) 

have   been  named  and  described  by  various  early  investigators, 
notably  Miller,'  and  Vicentini,^  later  byLeon  WiUiams'^andGoadby.* 

1  "Microorganisms  of  the  J-luman  Mouth,"  1889. 

^International  Journal  of  Microscopy  and  Natural  Science,   i8g4-g5. 

^  "Conlriljulions  to  the  liacteriology  o[  the  Human  Mouth,"  Dental  Cosmos, 


''     Mycology  of  the  Mouth,"  1903. 


444  THE    ORAL    FLORA 

Some  of  the  organisms  have  bsen  identified  with  others  occurring 
more  or  less  widely  disseminated;  others,  owing  to  the  fact  that  they 
were  not  described  in  sufficient  detail  cannot  be  recognised  as  dis- 
tinct species  today.  Some  of  these  organisms  are  constantly  en- 
countered in  stained  preparations  from  the  mouth,  notably  in  the 
case  of  individuals  who  do  not  exercise  proper  care  in  cleansing  the 
oral  cavity;  also  in  the  material  which  collects  on  the  teeth  during 
sleep,  and  in  the  so-called  mucinous  plaques  (bacterial  plaques) 
which  form  on  the  surface  of  the  teeth.  Such  organisms  are  often 
found  microscopically  in  many  pathological  conditions,  not  as  causa- 
tive factors  but  as  accidental  contaminations.  Some  can  only  be 
recognised  by  their  morphological  characteristics,  owing  to  the  fact 
that  they  have  resisted  all  attempts  directed  toward  their  isolation 
and  study  in  artificial  media.  Possibly  some  have  been  isolated  and 
are  known  under  other  names,  it  being  a  well-known  fact  that  cer- 
tain organisms  differ  markedly  in  form  under  varying  conditions  of 
development,  as  it  were  in  different  phases  of  their  life  cycle. 

For  the  purpose  of  illustration,  suppose  we  refer  again  to  the  micro- 
scopic study  of  material  of  various  kinds  from  the  oral  cavity.  The 
most  important  of  the  organisms  concerned  in  pathological  condi- 
tions are:  various  types  of  cocci,  rod-shaped  organisms,  spiral  and 
thread  forms ;  these  have  been  isolated  and  studied  in  cultures.  There 
are  others  which  are  readily  isolated  which  have  no  pathological 
significance,  although  they  may  play  a  part  in  dental  caries.  Among 
such  organisms  are  the  following: 

Sarcina  alba,  lutea  and  aurantica. — These  develop  readily  on  arti- 
ficial media,  producing  respectively  no  pigment,  a  yellow,  and  an 
orange  pigment.  They  divide  in  three  planes,  the  cells  remaining 
approximated,  resulting  in  the  formation  of  cubical  masses.  These 
cocci  are  quite  large,  i  to  i.5ju  in  diameter,  non-motile,  non-spore 
forming,  and  are  positive  to  Gram's  stain. 

lodococcus  vaginatus  of  Miller  which  he  claimed  is  found  in  all 
unclean  mouths  occurs  singly,  or  in  short  chains,  and  gives  the  iodine 
reaction.  The  identity  of  the  organism  has  never  been  established: 
its  importance  is  probably  only  historical. 

Micrococcus  tetragenus  or  Sarcina  tetragena  is  observed  in  oral 
material,  appearing  as  small  cocci  from  0.6^  to  o.8/i  in  diameter  occur- 
ring in  groups  of  four.  This  organism  is  at  times  noticed  in 
pathological  conditions  as  a  secondary  invader. 

Of  the  rod-shaped  organisms  encountered,  those  worthy  of  men- 


ORAL    MICROBIOLOGY 


445 


tion,  beside  the  pathogenic  organisms  aheady  considered,  are  the 
following : 

Bacillus  buccaUs  maxmms,  which  presents  as  jointed  threads  lo  to 
50yu  long  and  0.5  to  1.5/i  wide,  frequently  straight,  at  times  curved, 
positive  to  Gram's  method.  Flagella  are  present.  Goadby  has  iso- 
lated and  described  an  organism  under  this  name  which  apparently 
belongs  to  the  Mesentericus  or  Subtilis  groups  of  the  ordinary  spore- 
forming  soil  organisms.  Leptothrix  buccalis  of  VignaP  Sind  Leptothrix 
huccalis  maxima  of  Miller  are  probably  identical  with  the  above. 


Fig.  377. — Bacillus  buccalis  maximus.  Preparation  similar  to  Fig.  462. 
Magnified  800  times,  b.b.  Bacillus  buccalis  maximus;  b.  Large  rod-shaped  form; 
N.   Nucleus  of  partially-digested  epithelial  cell. 


Various  types  of  the  so-called  spore-forming  organisms  of  the  soil 
are  met  with  in  stained  preparations.  These  can  be  readily 
separated  in  cultures.  Among  them  we  find  the  Bacillus  subtilis; 
Bacillus  mesentericus  fuscus,  which  is  identical  with  the  Bacillus 
gangrence  pulpce  of  Arkovy;^  Bacillus  mesentericus  ruber  and  others. 

Non-sporulating  rod-shaped  organisms  of  various  types  may  be 
noted,    as    the   Bacillus   proteus  vulgaris,  Bacillus  coli — organisms 


1  Archives  de  physic)!.,  normal  path.,  1886. 

^  V ierldj ahresshriJL  fUr  Zahncilkunde,  Jahrgang,  xiv. 


446 


THE    ORAL    FLORA 


Fig.  378. — Various  forms  of  micro-organisms  from  the  mouth^direct.  The 
fine  threads  are  Miller's  Leptothrix  innominata:  the  thick  chain  is  Bacillus  huccalis 
maximus.      (From  Goadby's  "The  Mycology  of  the  Mouth.") 


Fig.  379. — Leptothrix  buccalis  maxima,  and  Bacillus  buccalis  Tnaximus.  From 
approximal  surface  of  a  tooth.  Magnified  1,500  times.  {Photomicrograph  by 
Leon  Williams.) 


ORAL    MICROBIOLOGY 


447 


Pig.   380. — Spirillum     sputugenum     from    mouth     direct.      Stained    with    gen- 
tian aniline  violet.      Magnified  1,000  times.     {Trans.  Odonto.  Soc.  of  Great 

Britain.) 


Fig.   381. — Spirillum  sputugenum  (comma  forms)   from  mouth  direct.     Stained 
and  magnified  as  in  preceding  Fig.  and  from  same  source. 


THE    ORAL    FLORA 

that  cannot  possibly  be  recognised  except  by  isolating  and  studying 
their  characteristics. 

Members  of  the  Spirillum  group  are  found  in  a  large  percentage 
of  cases.  The  organism  known  as  the  Spirillum  of  Miller,  Spirillum 
sputugemim,  or  Microspira  Milleri,  which  occurs  as  short  slender 
comma-shaped  cells,  is  not  infrequently  encountered.  The  only  way 
in  which  this  organism  can  be  differentiated  from  other  MicrospircB 
is  by  isolation  and  culturing. 

The  important  Spirochcetce  or  Treponemata  have  already  been 
considered. 


Fig.  382. — Spirillum  sputiigenum,  freshly  isolated  from  the  mouth.  Spiral 
forms  not  yet  well  developed.  Magnified  1,000  times.  (Trans.  Odonto.  Soc.  of 
Great  Britain.) 

Strikingly  interesting  organisms,  probably  more  interesting  than 
important,  are  certain  of  the  Chlamydobacieriacece  or  sheath  organ- 
isms. The  Cladothrix  dichotoma  is  occasionally  observed,  but 
cannot  be  distinguished  from  certain  other  thread-like  organisms, 
in  preparations  made  direct  from  the  oral  cavity.  In  cultures  it  is 
readily  differentiated  from  all,  excepting  the  Streptothrix  buccalis, 
and  from  this  by  careful  morphological  study.  It  occurs  in  the  form 
of  long  threads,  straight  or  curved,  apparently  branched.  It  is  of 
no  pathological  significance.  The  Leptothrix  innominata  of  Miller 
occurs  in  slender  threads  from  20  to  30^1  in  length  usually  straight, 
at  times  curved,  rarely  segmented,  frequently  presenting  small  gran- 


ORAL    MICROBIOLOGY  449 

ules.  This  organism  has  never  been  isolated  and  identified  as  such. 
It  presents  a  sheath  when  stained  t»y  appropriate  methods,  therefore 
it  would  appear  to  be  a  true  Leptothrix. 

The  so-called  Leptothrix  racemosa  of  Vicentini  is  very  frequently 
discovered  in  the  oral  cavity,  and  has  always  attracted  a  great 
deal  of  attention  on  account  of  its  striking  form.  Vicentini  at  one 
time  looked  upon  this  organism  as  the  parent,  as  it  were,  of  all  bac- 
teria found  in  the  sputum.  This  of  course  was  many  years  ago 
when  the  theory  of  pleomorphism  was  receiving  a  great  deal  of  un- 
deserved attention.  The  organism  has  never  been  isolated.  Where 
it  should  actually  be  placed  in  the  cryptogamic  classification  is  not 
known;  it  is  not  a  true  Leptothrix.  The  writer  has  suggested  on 
several  occasions  that  it  be  classified  for  the  present  with  the  Fungi 
imperfecti. 

It  has  been  studied  in  detail  morphologically  by  Vicentini  and 
Leon  Williams.  Owing  to  the  fact  that  the  organism  is  of  con- 
siderable historical  and  biological  interest,  if  probably  non-important 
pathogenically,  the  description  given  in  the  first  edition  of  this  book, 
reading  as  follows,  is  appended. 

"  Considerable  interest  has  lately  attached  to  the  Leptothrix  race- 
mosa, an  organism  first  described  by  Filandro  Vicentini  in  a  series 
of  contributions  to  the  International  Journal  of  Microscopy  and 
Natural  Science,  1894-1895,  entitled  the  'Bacteria  of  the  Sputa  and 
the  Cryptogamic  Flora  of  the  Mouth.'  By  a  special  method  of 
staining  he  discovered  the  organism  in  the  materies  alba  of 
Leuwenhoek.^  Preparations  were  made  before  the  first  morning 
meal.  This  highly  specialised  form  of  Leptothrix  is  said  to  resemble 
the  algse.  It  is  a  long,  thread-like  micro-organism  having  segmenta- 
tions or  subdivisions,  is  uncoloured  by  iodine  or  weak  acids,  and  at 
present  is  quite  uncultivable.  If  the  materies  alba  be  examined, 
it  will  be  found  to  contain,  beside  micrococci  and  bacilli,  long,  inter- 
lacing filaments,  non-jointed,  and  non-coloured  violet  by  iodine  or 
acid.  Vicentini  wished  to  change  the  term  Leptothrix  buccalis  to 
Leptothrix  racemosa  in  order  to  represent  its  sporulation.  This 
spore  formation  is  only  found  in  the  superficial  threads  of  the  mass, 
the  older  filaments  apparently  being  devoid  of  them. 

"The  female  element  consists  of  a  central  thread  or  stem,  peduncles 
arranged  in  six  rows,  sporules  and  a  gelatinous  envelope.  In  other 
words  Leptothrix  racemosa  is  a  thread-like  organism  found  in  the 

1  Opera  omnia  sive  arcana  naiiirw  ape  Microscopiorum  exaclissimonim  detecta. 
1722. 

29 


450 


THE    ORAL   FLORA 


Fig.  383. — Leplolhrix  racemosa.      {Pholomicrogyaph  by  Leon  Williams.) 


Fig.  384. — Leplolhrix  racemosa.      {Photomicrograph  by  Leon  Williams.) 


ORAL    MICROBIOLOGY 


451 


microbial  placques  of  the  interdental  spaces  during  the  hours  of 
fasting,  and  has  beaded  stems  which  bear  at  their  extremities  fructi- 
fying heads  containing  six  or  more  rows  of  spores  (Fig.  385). 

"Vicentini  considered  that  the  microorganism  passes  through  four 
phases  in  its  life  history.  First,  that  common  to  all  bacteria,  and 
undifferentiated  from  them;  second,  a  stage  of  transition,  in  which 


Fig.  385. — Lepiolhrix    racemosa.     "Fructification    heads."     From    approximal 
surface  of  a  tooth.      {Photomicrograph  by  Leon  Williams.) 

there  may  be  recognised  'chains,  bundles,  and  masses  of  inter- 
twined filaments,  isolated  filaments,  large  dumb-bell  bacteria,  and 
masses  of  diplococci,  the  large  dumb-bell  bacteria  being  derived 
from  the  diplococci,  the  true  original  cocci  Unking  together.'  The 
third  phase  occurs  with  the  deposition  of  tartar  on  the  teeth.  Here 
he  described  large  threads,  often  massed  together  in  bent,  filamentous 


452 


THE    ORAL    FLORA 


forms,  which  presented  the  pecuHar  appearances  of  branched  or 
barbed  radial  extremities  and  bulbous  terminations.  And  in  the 
last  phase,  which  Vicentini  called  that  of  'fructification'  or  'com- 
plete aerial  vegetation,'  the  fertile  heads  or  extremities  assume  a 
more  complicated  appearance,  and  exhibit  the  formation  of  spores 
arranged  in  three  longitudinal  rows.  'The  fertile  filaments  are 
sometimes  straight,  at  others  bent  or  curved,  occasionally  they  are 
entirely  wanting,  because  the  fructifications  have  been  carried  away 
by  mechanical  force.'  'Gemmules  of  reserve'  adhere  to  the  pe- 
riphery of  the  stem. 

"Vicentini  believes  that  in  its  method  of  reproduction  this  organism 
follows  two  methods — the  endogenous  spore  formation,  and  the  con- 
jugated fructification  or  acrogenous  ab junction,  in  which  spores  are 
found  at  the  apices  of  the  cryptogam.  The  terminal  cell  becomes 
enlarged  and  converted  into  a  tiny  base  called  the  basidium,  from 
which  arise  minute  stalks  or  sterigmata,  carrying  spores  upon  their 
terminal  ends. 

"In  this  way  it  is  possible  that  Leptothrix  racemosa  possesses 
veritable  organs  of  reproduction  and  therefore  resembles  fungi 
and  the  diascious  algae.  The  male  elements  have  a  morphological 
likeness  to  blossoms  formed  of  spindle  or  fern-shaped  points. 

"Vicentini  believed  that  this  micro-organism  is  the  parent  of  all 
but  one  of  the  varieties  found  in  the  sputum.  Thus  he  asserts  that 
Bacillus  huccalis  maximus  and  Leptothrix  buccalis  represent  merely 
its  broken  stems  and  filaments,  lodococcus  vaginatus  the  '  gemmules 
of  reserve,'  and  the  Spirillum  sputugenum,  the  appendages  or 
branches  of  the  male  elements. 

"Much  of  this  work  is  corroborated  by  Leon  Williams,  who,  how- 
ever, does  not  hold  entirely  with  ah  his  views." 

THE  MICRO-ORGANISMS  OF  DENTAL  CARIES 

The  organisms  found  in  dental  caries  are  of  various  types;  some 
active  in  the  various  stages  of  the  process,  others  simply  present  as 
accidental  invaders  and  of  no  significance  as  far  as  the  condition  is 
concerned. 

Miller  demonstrated  conclusively  that  dental  caries  was  caused 
essentially  by  bacterial  action,  isolating  bacteria  from  carious  teeth 
and  furthermore  producing  all  stages  of  caries  artificially. 

Goadby  grouped  the  organisms  of  dental  caries  into  three  classes: 
namely  those  having  the  property  of  (A)  forming  acid,  (B)  of 
peptonising   dentine;   and    (C)   producing  pigmentation.     He  also 


ORAL    MICROBIOLOGY 


453 


mentions  a  number  of  organisms  found  in  a  group  of  cases 
studied.  Our  experience  has  been  that  the  organisms  encountered 
in  the  mouth  and  in  the  various  stages  of  dental  caries  vary  to  a 
great  extent  and  that  by  special  methods  of  cultivation,  some  are 
noticed  which  ordinarily  are  not  found.  Therefore  it  seems  out 
of  place  in  this  chapter  to  attempt  to  name  all  of  the  different 
organisms  concerned  in  the  process. 

The  organisms  concerned  in  the  various  stages  may  be  grouped 
as  follows: 

I.  Those  entering  into  plaque  formation.  Various  types  of  cocci, 
baciUi,  leptothrix  and  streptothriciae.  These  have  been 
considered  in  sufficient  detail  under  the  findings  in  stained 
preparations. 

II.  Those  concerned  in  acid  formation.  To  attempt  to  name  and 
consider  all  organisms  associated  with  dental  caries  would  be 
inexcusable  in  this  chapter;  the  following  statement  covers  the 
entire  situation.  Any  organism  capable  of  developing  in  the 
oral  cavity,  and  of  forming  acids  by  splitting  carbohydrates, 
may  play  a  part  in  dental  caries  by  forming  organic  acids,  the 
most  important  of  which  are  acetic  and  lactic,  which  by  their 
constant  or  intermittent  action,  notably  on  protected  surfaces, 
underneath  plaques,  etc.,  disintegrate  enamel.  Butyric  and 
succinic  acids  are  also  formed,  and  they  are  claimed  by  some  to 
exert  a  similar  action. 

Some  speak  of  acid-producing  organisms  in  this  connection  and 
actually  beheve  that  the  organisms  produce  acids.  The  facts 
are  as  follow:  The  micro-organisms  produce  enzymes  of 
various  kinds,  some  of  which  have  the  property  of  splitting  up 
carbohydrates  into  simpler  compounds,  amongst  which  are  the 
acids  already  named. 

III.  Those  disintegrating  dentine: 

(A)  Acid  formers  as  above,  the  acid  dissolving  the  hme  salts 
in  the  dentine. 

(Bj  Various  organisms  capable  of  digesting  proteins.  This 
might  include  any  organism  capable  of  developing  in  the 
oral  cavity  producing  proteolytic  enzymes  or  decarb- 
oxylases and  deamidases.  The  above  groups  may  be 
divided  as  follows: 

{a)  Those  acting  on  the  superficial  layers  of  carious  dentine. 
(i)  Aerobic:   those   acting    (developing)    only  in   the 
presence  of  free  oxygen. 


454  THE    ORAL    FLORA 

(2)  Aerobic    facultative:    those    acting    both    under 
aerobic  and  anaerobic  conditions  (Fig.  146). 
(b)  Those  acting  on  the  deeper  layers  of  carious  dentine. 

(i)  Aerobic  facultative. 

(2)  Anaerobic:  Those  not  capable  of  developing  in  the 
presence  of  free  oxygen,  but  growing  only  under 
strict  anaerobic  conditions.  The  conditions  in 
deeper  caries,  underneath  masses  of  food-debris- 
filled  cavities,  and  underneath  temporary  and 
permanent  fillings,  are  ideal  for  their  development. 


Fig.  386. — Bacillus  necrodenialis .  Showing  pleomorphism.  Forty-eight 
hours'  cultivation  of  agar.  Stained  by  Gram's  method.  (Magnified  i,ooo 
times.      {Trans.  Odonto.  Soc.  of  Great  Britain.) 


Bacterial  proteolytic  enzymes  are  of  two  types:  (i)  Of  the  nature 
of  pepsin,  carrying  the  cleavage  of  protein  as  far  as  the  formation 
of  peptone;  (2)  Of  the  nature  of  trypsin  carrying  the  cleavage  of 
protein  so  far  as  the  formation  of  amino  acids. 

The  so-called  putrefactive  changes  in  caries,  made  manifest  by 
the  presence  of  a  decided  aromatic  odor,  are  due  to  the  end-products 
formed  by  the  deamination  and  decarboxylisation  of  the  amino 
acids,  chiefly  some  of  the  higher  open  chain  acids  and  those  of  the 
benzene  series.  This  action  is  exerted  by  various  types  of  bacteria 
under  anaerobic  conditions. 

The  organisms  in  the  deeper  layers  of  carious  dentine  have  been 
the  subject  of  some  investigation  and  much  discussion.     The  pre- 


ORAL    MICROBIOLOGY  455 

vailing  opinion  is  that  they  are  not  numerous.  "Goadby  gives  as 
quite  constantly  present  an  organism  which  he  isolated  and  called 
the  Bacillus  necrodentalis,  the  Streptococcus  brevis,  and  Staphylo- 
coccus albus.  The  first  is  an  anaerobe,  the  other  two  facultative. 
Organisms  of  the  so-called  Moro-Tissier^- group  of  intestinal  bacteria 
have  been  found  in  the  deeper  layers  of  carious  dentine  by  Kleigler,^ 
Howe^  and  others.  Their  relationship  to  the  process  is  apparently 
an  important  one. 

1  Jahresberichte  fiir  Kinderheilkunde,  1900  and  1905. 

2  Annales  de  rinstiliit  Pasteur,  1900. 
^Journal  of  Allied  Dental  Societies,  iQiS- 
*  Journal  of  Medical  Research,  1917. 


PART  III 
THE  EXTRA-ORAL  DENTAL  TISSUES 


CHAPTER  XVII 

"DERMOID"  TEETH,  OR  TEETH  DEVELOPED  IN 
TERATOMATA 

Relation  of  teeth  to  Teratomata — Varieties — Eruption — Development — 
Shedding — Anatomy  and  Histo-pathology — Bony  attachments — 
Relation  of  "Dermoid"  teeth  to  Hair — "Dermoid"  teeth  in  the 
testis — Conclusions. 

"Dermoid"  teeth,  or  teeth  developed  in  teratomata,  are  of  in- 
terest to  the  embryologist,  the  pathologist,  the  surgeon,  and,  to 
the  dentist.  Teeth  appearing  elsewhere  than  in  the  maxilla  or  the 
mandible  must  be  considered  as  abnormal.  The  origin  of  such 
is  now  beheved  to  be  almost  certainly  connected  in  every  case  with 
a  teratoma.  These  teratomata  occur  most  commonly  in  the  ovary, 
in  the  neck,  and  possibly  in  the  testis.  They  are  seen  in  the  human 
subject,  and  also  in  animals  of  a  lower  grade.  When  occurring  in 
the  neck,  a  teratoma  is  probably  an  anterior  dichotomy,  abortive 
in  most  cases.  These  remarks  are  confined  to  the  dental  structures 
which  are  by  no  means  infrequently  discovered  in  those  cysts  not 
uncommonly  associated  with  the  human  ovary,  and  have  been  for 
long  termed  "dermoid  cysts." 

In  i860,  Salter  1  pubHshed  an  excellent  account  of  these  teeth, 
while  in  1863  Alfred  Coleman^  presented  another.  In  1890 
T.  Charters  White  and  J.  Bland-Sutton^'  jointly  read  a  most  in- 
structive contribution  to  the  subject,  and  later  S.  G.  Shattock* 
summarised  in  a  brilliant  article,  the  then-existing  knowledge  of  the 
subject. 

"dermal"  tissues 

An  ovarian  "dermoid"  is  a  true  teratoma. 

It  is  interesting  to  note  that  it  is  what  may  be  called  the  "  dermal " 
tissues  which  seem  to  be  most  in  evidence.  There  is  abundance  of 
skin,    often    much    hair,    and    this    of    two    kinds,    fine    lanugo- 

'  Guy^s  Hosp.  Reports,  i860. 

2  Trans.  Odont.  Soc.  of  Great  Briiain  (1863-65),  1865. 

'  Denial  Record,  1890. 

''  Trans.  Palh.  Soc,  1907. 

459 


460 


THE    EXTRA-ORAL    TISSUES 


like,  and  long  and  scalp-like,  each  growing  from  its  own  appropriate 
part  of  the  foetus,  and  teeth,  sometimes  only  one,  often  many,  and 
occasionally  exceedingly  numerous.  Also  in  a  few  instances  nails 
or  horny  structures  have  been  observed. 

RELATION  OF  TEETH  TO  TERATOMATA 

The  exact  position  of  these  teeth  in  relation  to  the  teratomatous 
tissue  and  to  the  actual  cvst  wall  is  a  matter  of  some  interest  and 


s 

m 

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^^^^^B 

^^^1 

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~^^^^^H 

Hi 

/^H 

H 

Hi 

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T 

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^^ 

~ife 

l^yjy"              ^^^^t 

T  T 
TTT 

|^B^_^  ■,  , 

-n.V' 

1 

c  w. 


c  c 


Fig.  387. — An  ovarian  teratomatous  cyst  laid  open  to  show  contents,  c.w. 
Cyst  wall;  c.c.  Cyst  cavity;  t.  Caniniform  tooth;  t.t.  Another  portion  of  the 
teratoma,  possibly  an  arm;  t.t.t.   Possibly  the  scalp. 

importance.  The  teeth  may  be  found  (i)  embedded  in  bone  in 
actual  alveoli  or  sockets,  (2)  embedded  in  soft  tissue,  either  of  the 
foetus  or  possibly  of  the  cyst  wall,  or  (3)  free  within  the  cyst  cavity. 
There  is  no  reason  why  a  teratomatous  foetus  should  not  possess 
an  ill-formed  maxilla  or  mandible,  and  no  reason  why  such  a  jaw 


TEETH  DEVELOPED  IN  TERATOMATA 


461 


should  not  carry  teeth.  Hence  the  appearance  on,  or  in  the  tissue 
forming  the  foetus,  of  bone  with  attached  teeth  is  easy  of  explana- 
tion; but  it  is  difficult  to  account  for  those  instances  where  teeth 
have  been  found  at  some  distance  apparently  from  the  actual  site 
of  the  foetal  tissues,  and  attached  to  soft  tissues  only.  There  are 
three  possible  explanations:  First,  that  during  the  development  of 
the  cyst,  associated  with  which  is  the  foetus,  pressure  has  caused  a 
lateral  displacement  of  a  part  of  the  fcetus,  so  that  the  tooth-bearing 
area  has,  as  it  were,  become  flattened  out,  leading  to  an  elongation 


TTT 


C  W 


Fig.  388. — A  portion  of  an  ovarian  teratomatous  cyst  laid  open  to  show  con- 
tents. C.W.  Cyst  wall;  b.  Bone  t.o  which  teeth  were  attached;  T.  Caniniform 
tooth;  T.T.   Premolariform  tooth;  t.t.t.  Molariform  tooth. 


of  the  tooth  band.  Secondly,  there  may  have  been  a  homologous 
twin  which  has  developed  very  much  less  than  its  fellow,  in  fact, 
the  teeth  may  be  the  sole  evidence  of  its  existence.  It  is  possible  for 
the  same  ovary  to  contain  three  separate  teratomata,  or  triplets,  and 
thus  for  the  number  of  teeth  present  to  be  considerable,  and  their  posi- 
tion remote  in  relation  to  the  obvious  teratoma.  Or,  thirdly,  it  may 
be  an  anterior  dichotomy  of  the  teratoma,  thus  allowing  for  at  least  a 
second  dentition. 

It  is  always  the  cephalic  end  of  the  teratoma  in  which  these  "der- 


462  THE    EXTRA-ORAL    TISSUES 

moid"  teeth  arise,  and,  in  fact,  the  dental  structures  may  in  some 
instances  be  the  only  evidence  of  the  cephalic  end  of  a  trunkless 
(acormous)  teratoma. 

VARIETIES 

The  morphological  variations  in  teeth  associated  with  ovarian 
teratomata  approximate  very  closely  to  those  usually  found  in  the 
human  mouth.  Incisors,  canines,  premolars  and  molars  have  their 
counterparts  in  these  cysts.  The  premolariform  and  caniniform 
types  predominate  from  the  point  of  view  of  number.  The  teeth 
themselves  are  generally  well  developed,  and  bear  few,  if  any,  traces 
of  any  degeneration  of  their  exposed  portions.  Seldom,  if  ever, 
have  purely  conical  representatives  been  noticed  in  these  cysts. 
Sometimes,  however,  very  numerous  malformed  dental  bodies  are 
met  with.  These  possess  but  little  resemblance  to  ordinary  human 
teeth. 

The  cause  of  such  enormous  quantities  of  these  denticles  is 
difficult  to  determine.  It  may  be  that  an  extended  tooth  band  has 
given  rise  to  myriads  of  aborted,  but  more  or  less  calcified,  tooth 
germs.  Or  that  fenestration  and  total  disappearance  of  the  inter- 
vening portions  of  the  tooth  band  have  occurred  in  the  usual  way, 
and  that  arrest  of  complete  development,  caused  by  the  abnormal 
environment  to  which  they  have  been  subjected,  coupled,  perhaps, 
with  the  precocity  and  rapidity  of  their  growth,  has  resulted  in  the 
display  of  congeries  of  misshapen,  irregular  masses  composed  mainly 
of  enamel  and  dentine.  Although  these  teratomatous  cysts  are 
tooth-bearing  cysts,  they  are  in  no  sense  dentigerous  cysts,  and  it 
would  appear  to  be  extremely  likely  that  the  same  operations  of 
pathogenesis  may  be  acting  here  as  in  similar  fashion  to  those  which 
act  sometimes  in  the  jaws.  It  is  not  beyond  the  bounds  of  possi- 
bility that  there  may  be  occasionally  a  multiplicity  of  tooth-bearing 
cysts,  which  ultimately  are  capable  of  becoming  incorporated  in 
one  large  cavity. 

DEVELOPMENT 

In  "dermoid"  oophoronic  cysts  "epithelial  pearls"  exist.  The 
cells  are  large,  become  compressed  as  they  approach  the  peripheral 
portion  of  the  "pearl,"  and  are  finally  lost  in  the  surrounding  cap- 
sule. They  are  ingrowths  from  the  surface  epithelium,  which  be- 
come isolated  in  the  mesodermic  tissue,  and  are  allied  to  enamel 
organs,  being  attached  to  the  free  surface  where  they  arose.     Many 


TEETH  DEVELOPED  IN  TERATOMATA 


463 


ovarian  tooth  germs  lack  a  definite  fibrous  capsule.     (See  Fig.  256, 
Vol.  I.) 

The  so-called  "pearls"  may  remain  cellular,  or  give  rise  to  the 
formation  of  enamel,  or  undergo  transformation  into  horns  or  nails. 

ERUPTION   OR   NON-ERUPTION    OF    TEETH 

Of  the  actual  dynamics  of  the  eruption  of  ovarian  teeth  it  is  impos- 
sible to  speak.  Many  of  the  oral  conditions  which  assist  this  phe- 
nomenon are  entirely  absent.  The  growth  of  bone  when  present  may 
have  some  bearing  upon  the  eruption,  but  this  cannot  hold  in  those 


Fig.  389. — Part  of  the  contents  of  an  ovarian  "dermoid"  cyst.  t.  Three 
well-formed  premolariform  teeth;  h.  A  bundle  of  hair;  a.  Amass  of  teratomatous 
bone.      (Photograph  by  Mr.  Dencer  Whittles.) 


instances  in  which  teeth  are  erupted  from  the  wall  of  the  "dermoid" 
in  places  where  no  bone  exists. 

Many  cysts  contain  enamel  organs  which  have  not  proceeded  to 
maturity.  It  would  seem  that  many  teeth  while  fully  developed, 
except  perhaps  as  far  as  their  roots  are  concerned,  do  not  become 
extruded  through  the  superficial  soft  parts,  though  evidences  are 
not  wanting  that  generally,  by  virtue  of  their  rapid  and  precocious 
growth,  they  do  completely  erupt  on  the  surface  of  the  teratoma. 

There  is  no  evidence  of  any  eruf)tion  of  a  second  dentition  such 
as  occurs  in  the  normal  mouth. 


464 


THE    EXTRA-ORAL    TISSUES 


SHEDDING 

In  the  ovarian  embryomata  hair  is  frequently  shed.  The  same 
cause  may  be  at  work  in  producing  this  separation  as  in  the  case  of 
other  epidermal  derivatives.  The  implantation  of  the  ovarian 
teeth  is  comparatively  feeble  in  character.  They  are  retained  in 
the  fresh  condition  by  a  thin  annular  elevation  of  connective  tissue 
at  their  necks,  and  in  many  dried  specimens  there  is  an  appearance 
as  if  the  marginal  bone  had  become  absorbed,  or,  at  all  events, 
had  never  been  fully  developed.     The  necks  of  the  teeth  are  well 


Fig.  390. 


-Vertical  section  of  the  enamel.      Magnified   55  times,      e.   Enamel. 
D.  Dentine.      A.  Amelo-dentinal  junction. 


exposed  and  vary  in  depth,  and  often  their  roots  are  visible  above 
the  free  surface  of  the  bony  alveolus. 

It  is  possible  that  when  a  tooth  is  found  free  within  the  cavity  of 
the  cyst,  it  has  been  shed  by  senile  changes,  in  an  acardiac,  acor- 
mous  parasite  as  part  of  a  pathological  retrogression  which  is  en- 
tirely different  from,  and  antecedent  to,  that  of  the  host.  But  iii 
other  cases  it  may  but  be  an  accidental  detachment  during  the  re- 
moval of  the  cyst  from  the  body. 


ANATOMY   AND   HISTO-PATHOLOGY 


For  the  most  part  the  teeth  found  in  ovarian  teratoma  ta  exhibit 
the  main  characteristics  of  those  of  the  human  permanent  denti- 


TEETH  DEVELOPED  IN  TERATOMATA 


46s 


tion,  though  on  the  whole  they  are  snlaller.  In  those  examined 
they  measured  about  5.5  mm.  in  their  extero-internal  diameter 
(which  would  correspond  to  the  bucco-lingual  direction  in  the  mouth) 
and  17  mm.  in  extreme  length.  But,  of  course,  many  variations 
of  mensuration  are  met  with.  In  those  specimens  specially  exam- 
ined for  the  purpose,  the  translucent  pellicle  of  Nasmyth's  mem- 
brane was  found. 


1)  z 


Fig.  391. — Vertical  section  of  an  ovarian  tooth.  Decalcified.  Stained  with 
hsematoxylene.  Magnified  45  times,  d.  Dentine;  p.  Pulp  tissue;  o.  Odonto- 
blasts; D.z.   Dentogenetic  zone. 


A  root  is  generally  present,  being  joined  to  the  crown  sometimes 
without  the  usual  cervical  constriction.  Seldom  is  a  tooth  bi-rooted, 
and  a  multi-rooted  tooth  is  very  rare.     The  roots  taper  to  a  point. 

On  section  a  pulp  cavity  with  root  canal  can  usually  be  observed. 
In  extremely  thin  incisiform  specimens  this  is  often  narrowed  down  to 
an  inconspicuous  canal,  and  even  this  at  times  may  be  wanting. 
In  the  fresh  condition  pulp  tissue  is  present,  and  bundles  of  myelinic 
nerve  fibres  can  be  seen  accomi)anying  the  blood-vessels.  When  no 
30 


466 


THE    EXTRA-ORAI    TISSUES 


D  Z 


Fig.  392. — Section  of  an  ovarian  tooth  with  pulp  in  situ.  Stained  with 
haematoxylene.  Magnified  200  times,  d.  Dentine,  d.z.  Dentogenetic  zone;  p. 
Pulp;   O.   Odontoblasts. 


Pig.   393. — Siniilar  to  preceding  figure,      d.  Dentine;  o.  Odontoblasts;  n.   Mye- 
linic nerve  fibres. 


TEETH  DEVELOPED  IN  TERATOMATA 


467 


actual  cavity  exists,  dentinal  tubules  radiate  more  or  less  from  a 
common  centre  outwards,  but  in  some  sections,  the  tubules  run 
centripetally  as  well  as  centrif ugally  (Fig.  65). 

Enamel,  dentine  and  cementum  are  present.  The  first  is  fairly 
normal,  the  second  of  an  incompletely  developed  character,  as 
proved  by  the  abundance  of  interglobular  spaces.  Cementum  is 
frequently  absent.  If  it  is  present,  it  constitutes  a  very  thin  external 
band  of  the  dentine,  just  beyond  the  homogeneous  layer  and  the 
granular  layer  of  Tomes.  The  pathology  of  these  teeth  has  been 
cursorily  described  by  Wedl  (Atlas  der  Path,  der  Zahne,  1903).  He 
believes  that  erosion  of  the  superficial  parts  may  take  place.     He 


Fig.   394. — Similar    to    preceding,      d.   Dentine;    p.    Pulp;   o.    Odontoblasts;  N. 
Myelinic  nerve  fibres. 


has  not  seen  dental  caries,  which  is  to  be  expected,  inasmuch  as  the 
contents  of  the  embryomatous  cyst  are  generally  of  a  thick  alkaline 
nature,  and  suppuration  often  occurs.  Mr.  Shattock  says  that 
enamel  nodules  may  sometimes  be  seen  upon  the  roots.  The 
teeth  are  clumped  together,  and  are  malplaced  when  found  embedded 
in  the  teratomatous  bone.  Instead  of  occupying  a  definite  relation- 
ship to  each  other,  as  in  the  mouth,  they  are  placed  irregularly 
with  regard  to  one  another,  possibly  from  the  fact  that  here  there  are 
no  mechanical  factors  such  as  are  produced  by  the  action  of  the  soft 
tissues  of  the  tongue  and  cheek  or  lips  in  giving  rise  to  the  proper 
alignment  of  the  teeth  in  the  dental  arch. 


468  THE    EXTRA-ORAL    TISSUES 

BONY  ATTACHMENTS 

Some  of  the  pieces  of  bone  in  which  these  ovarian  teeth  have  been 
found  are  exceedingly  hke  small  maxills  or  ill-developed  mandibles. 
One  peculiarity,  however,  is  often  present,  namely,  that  whereas  the 
size  of  the  "jaw"  itself  is  much  less  than  the  size  of  the  jaw  of  the 
host,  the  teeth  themselves  found  in  the  ovary  may  be  almost,  if  not 
quite,  as  large  as  those  found  in  the  normal  mandible  of  the  host. 
The  bone  itself  is  of  poor  quality,  and  consists  mainly  of  cancellous 
tissue. 

RELATION   OF    '' DERMOID"    TEETH   TO   HAIR 

As  a  rule  the  teeth  in  the  teratomata  of  the  ovary  bear  no  relation- 
ship to  the  hair  growing  from  the  same  parasite,  other  than  that 
they  will  be  found  in  their  own  normal  position  in  reference  to  the 
cephalic  end  of  the  teratoma,  and  the  long  hairs  will  be  springing 
from  the  scalp  portion  of  the  foetus,  also  at  the  cephalic  end.  But 
sometimes  short,  rather  stubbly  hairs  are  found  growing,  in  a  ringlet, 
actually  round  the  neck  of  the  tooth  from  the  soft  tissue  which  might 
be  said  to  be  forming  the  gum.  This  fact  is  interesting  as  showing 
the  close  possible  connection  between  the  two  dermal  structures, 
hairs  and  teeth.    ' 


X-RAY   EXAMINATION    OF       DERMOID       TEETH 

The  X-ray  examination  of  "dermoid"  teeth  is  interesting  from 
several  points  of  view.  The  teeth,  like  normal  teeth,  obstruct  the 
passage  of  the  rays  more  markedly  than  does  the  bone  by  which 
their  roots  may  be  surrounded.  Hence  it  is  quite  possible  that  an 
X-ray  examination  of  a  living  subject  who  is  the  host  of  a  dermoid 
cyst  of  the  ovary  might  reveal  the  presence  of  the  cyst  by  the  marked 
shadow  thrown  by  the  teeth,  if  any  were  present,  in  contrast  to 
the  shadow  thrown  by  the  pelvic  bones. 

A  radiograph  will  also  indicate  the  presence  of  a  pulp  cavity  in  the 
interior  of  the  "dermoid"  teeth.  It  will  also  show  the  character 
of  the  bone  associated  with  the  teeth,  if  any  bone  exists. 

"dermoid"    teeth   IN   THE   TESTIS 

There  are  on  record  several  cases  of  a  dermoid  cyst  of  the  testis 
in  the  human  subject,  but  the  condition  must  be  considered  as  an 


TEETH   DEVELOPED    IN    TERATOMATA  469 

extremely  rare  one.  A  similar  cystic  enlargement  of  the  testis  of  the 
horse  is  not  so  uncommon,  and  particularly  where  the  testis  is 
retained.  One  case  at  least,  occurring  in  the  human  subject,  pre- 
sented a  tooth  borne  by  a  teratoma  in  the  testis.  In  the  case  of  the 
horse  there  have  been  found  similar  teeth. 

While  the  origin  of  ovarian  "  dermoids"  may  now  be  considered  as 
settled,  it  is  difficult  to  conceive  that  the  testis  can  be  the  host  of  a 
teratoma  with  an  identical  origin.  Prof.  Shattock  has  put  forward 
the  suggestion  that  these  "dermoids"  of  the  testis  are  in  reahty 
teratomata  of  the  ovary  portion  of  an  ovi-testis  gland  in  a  true 
hermaphrodite.  This  is  certainly  quite  feasible,  and  some  amount 
of  confirmation  is  obtained  from  the  presence  of  a  teratoma  asso- 
ciated with  an  imperfectly  descended  testis  in  a  "rig"  horse.  Such 
an  animal  is  not  infrequently  vicious  and  unsuitable  for  domestic 
purposes.  The  removal  of  the  retained  testis  has  the  effect  in 
many  instances  of  rendering  the  animal  docile  and  useful. 

CONCLUSIONS 

The  presence  of  teeth  in  dermoid  cysts  of  the  ovary,  and  of  the 
testis,  tends  to  prove  the  teratomatous  nature  of  these  tumours. 

The  similarity  between  dermoid  cyst  teeth  and  those  of  the  normal 
human  mouth  tends  further  to  indicate  their  teratomatous  origin. 

The  period  of  eruption  of  the  "dermoid"  teeth  does  not  coincide 
with  the  period  of  eruption  of  the  teeth  of  the  host,  but  is  probably 
earlier,  and  their  growth  is  more  rapid.  It  is  possible  that  this 
precocity  may  be  due  to  the  influence  of  the  super-host  through  her 
blood. 

There  is  no  distinct  evidence  of  the  shedding  of  "dermoid" 
teeth,  and  there  is  no  evidence  of  any  distinction  between  a  deciduous 
and  a  permanent  dentition. 

While  "dermoid"  teeth  may  be  ill-shapen  and  may  otherwise 
deviate  from  the  form  of  normal  teeth,  there  is  no  evidence  of  any 
pathological  process  which  can  be  termed  "caries." 


INDEX  TO  VOL.  II 


Abrasion  of  enamel,  22 

Abscess  of  periodontal  membrane,  255 

Of  pulp,  159 
Absorption  of  dentine,  55 

Of  enamel,  23 

Pathological,  25,  55,  59,  282 
Ackery    and   Colyer  on  absorption  of 

dentine,  68 
Actinomycosis,  437 
Acts,  obscure  reflex,  223 
Acute  caries,  no 

Adenoma,  330,  343,  352,  353,  400,  401 
Adventitious  bacteria  of  mouth,  443 
Adventitious    dentine,    71,    157,    164, 
210,  215 

Areolar,  72 

Cellular,  72 

Fibrillar,  73 

Hyaline,  74 

Laminar,  76 
Alexins,  153 

Alveolo-dental  periosteum,  abscess  of, 
255 

Carcinoma  of,  268 

Cyst  of,  258 

Degeneration  of,  306 

Fibroma  of,  225 

Inflammation  of,  254 

Morbid  Affections  of,  254 

Sarcoma  of,  265 

Tumours  of,  264 
Angina  Liidovici,  427 
Angioma,  328,  342 
Ankylosis  of  teeth,  80 
Anthrax,  433 
Antrum    of    Highmore,    adenoma    of, 

352,  353 

Carcinoma  of,  349 

Inflammation  of,  349 

Sarcoma  of,  329,  352 
'Aphthous  stomatitis,  354 
Areolar  adventitious  dentine,  72 


"Arrested  caries,"  138,  213 
Ascomycetes,  413,  420 
Atrophy  of  pulp,  195 
Attrition  of  enamel,  29 

Bacillus  aerogenes  capsulatns,  420,  434 
Bacillus  anthracis,  420,  433 

Buccalis  maximtis,  445 

Coli,  445 

Diphtheria,  420,  431 

Fluorescens     liquefaciens    motilis, 
140 

Furvus,  140 

Fiisiformis,  420,  438 

Gangrenes  pulpce,  445 

InfluenzcB,  420 

Mallei,  420,  433 

Mesentericus  fuscus,  445 

Mesentericus  ruber,  445 

Mucosus  capsiilatus,  420,  433 

Necrodentalis,  140,  209,  455 

Plexiformis,  140 

Proteus  vulgaris,  445 

Pseudo-dip htheriticum,  420 

Suhtilis,  140,  445 

Tetani,  420,  434 

Tuberculosis,  420,  422,  432 
Bacteria,  411 
Bacterium,  414 

Baker,    A.  W.  W.,  on  absorption  of 
dentine,  57,  58 

On  dental  cysts,  262 
Basidiomycetes,  413 
Baume  on  erosion  of  enamel,  31 

On  translucent  zone  of  caries,  1 20 
Beggiatoacece,  415 

Bennet  on  absorption  of  dentine,  66, 
67,  68 

On  translucent  zone  of  caries,  118 
Black  on  absorption  of  dentine,  58 

On  atrophy  of  pulp,  190 

On  calcification  of  pulp,  179 


471 


472 


INDEX 


Black  on  changes  in  dentine,  208,  209 
Bland-Sutton  on  absorption  of  teeth, 
S8 
On  odontomes,  371,  381 
Blastomyces  dermatitis,  440 
Blastomycetes,  39,  440 
Bone,  osteoporous  atrophy  of,  283 
Bretland  Farmer,  Moore  and  Walker  on 

cancer,  367 
Bryophyta,  413 

Buckley  on  putrefaction  of  pulp,  169 
"Burrowing  epithelioma"  of  jaws,  268 

Calcareous  degenerations     of    pulp, 

196,  231 
Calcott  Fox  and  McLeod  on  Paget's 

disease,  368 
Cancrum  oris,  354,  439 
Capsule  of  odontomes,  394 
Carcinoma  of  antrum,  349 

Columnar,  344 

Diagnosis  of,  328 

Of  jaws,  344 

Of  periodontal  membrane,  268 

Spheroidal-celled,  344 

Squamous-celled,  344 
Caries  acuta,  loi 
Caries  "arrested,"  138,  213 

Chronic,  74,  loi 

Chronica,  loi 

Humida,  loi 

Sicca,  loi 
Caush  on  absorption  of  dentine,  65,  66 
Cell-nests,  346,  347,  360 
Cellular  adventitious  dentine,  72 
Cemental  nodules,  80,  372,  385 
Cementomes,   372,   385 
Cementum,  ankylosis  of,  80 

Hyperplasia  of,  86 

Pathological  conditions  of,  80 

Senile,  100 
Charbon,  435 
Chemiotaxis,  153 
ChlamydohacteriacecE,  415 
Cladothrix,  415 

Cladothrix  dichotoma,  438,  448 
Classification   of   Bacteria   and  Proto- 
zoa, 413,  415 

Of  plants,  412 


CoccacecE,  413 

"Coccidia,"  360 

Composite  odontomes,  371,  372,  391 

Congenital  pigmentation  of  dentine,  53 

Crenothrix,  415 

Cryptogams,  411,  412 

Cuneiform  defects  in  enamel,  30 

Cyst,  dental,  258 

Dentigerous,  372 

Differential  diagnosis  of,  401 

Eruption,  381,  401 

Of  teeth  (odontocele),  399 

Degenerations  of    the  oral  mucous 
membrane,  354 

Calcareous,  196,  231 

Fatty,  196 

Fibroid,  187 

Malignant,  356 

Of  the  periodontal  membrane,  306 

Of  the  pulp,  atrophic,  195 
Dental  caries  {see  Caries). 
Dental  cyst,  258,  329,  330,  352,  372,  400 

Baker,  A.  W.  W.  on,  260,  262 

Turner  on,  260,  262 
Dental  pulp,  atrophy  of,  195 

Calcification  of,  177,  180,  196 

Carious  lesions  of,  207 

Degenerations  of,  187 

Diseases  of,  143 

Dysesthesia  of,  226 

Gangrene  of,  168 

Healing  processes  in,  182,  183 

Hypersemia  of,  144 

Hypersesthesia  of,  226 

Hyperplasia  of,  165 

Inflammation  of,  151,  164 

Injuries  of,  174 

Nodules  of,  198,  202 

Non-carious  lesions  of,  219 

Pathology  of,  143,  206 

Physiological  resistance  of,  210 

Putrefaction  of,  169 

Receptivity  of,  226 

Vascular  lesions  of,  232 
Dentigerous  cyst,  372 
Dentine,  absorption  of,  55 

Adventitious,   71,   157,   164,   210, 
21S 


INDEX 


473 


Dentine,  bone  in,  68,  69 

Caries  of,  115,  130,  132,  135,  142 

Congenital  pigmentation  of,  53 

Defects  of,  51 

Dilaceration  of,  42 

Gemination  of,  43 

Nanoid,  54 

Pathological  pigmentation  of,  76 

Senile,  76 

Syphilitic,  21 

Vascular  canals  in,  55 

"Of  repair,"  34,  205 
Dentz.on  defects  in  dentine,  51 
"Dermoid"  teeth,  459 
Diagnosis  of  cysts  of  jaws,  401 

Of  fluid  swellings  of  jaws,  329 

Of  inflammation  of  pulp,  255 

Of  sarcoma  and  carcinoma,  328 

Of  stomatitis,  354 

Of  swelling  of  mandible,  331 

Of  swellings  of  palate,  330 

Of  tumours,  327 
Differential     diagnosis     of     cysts     of 
jaws,  401 

Of  pulpitis  and  periodontitis,  255 

Of  stomatitis,  354 

Of  swellings  of  jaws,  329 
Dilaceration,  42 
Diphyodontic  gemination,  50 
Diplococcus  pneumonia,  139,  420 
Disturbances  of  sensation,  236 
Dolamore  on  composite  odontome,  391 
Duckworth  on  fungoid  excavation  of 
enamel,  39 

Enamel,  abrasion  of,  22 
Absorption  of,  23 
Attrition  of,  29 
Caries  of,  107,  141 
Channelling  of,  37 
Erosion  of,  30 
Excavation  of,  34 
Hypoplasia  of,  4 
Nanoid,  16 
Nodules,  9,  372 
Pigmentation  of,  14 
Rachitic,  18 
Syphilitic,  19 
Zsigmondy  on  hypoplasia  of,  5 


Enchondroma,  331 
Endamceba,  415,  418 
Endamceha  gingivalis,  418,  442 
Endospores,  411 
Endosteal  fibroma,  333 
Endothelioma  of  jaws,  340 
Epithelial  odontomes,  372 
Epithelioma,  344 

"Burrowing,"  268 
Erosion  of  enamel,  30 

Theories  of,  31 

Znamensky  on,  31 
Eruption  cysts,  381,  400,  401 
EubacteriacecB,  4r3 
Euthallophyta,  413 
Exostosis  of  jaws,  349 
Extensive  absorption  of  dentine,  59 
External  absorption  of  dentine,  57 

Of  enamel,  23 
Extra-capsular  odontocele,  404 

False  gemination,  43,  44,  46,  47 
Fatty  degeneration  of  pulp,  196 
Fibrillar  adventitious  dentine,  73 
Fibroid    degeneration    of    periodontal 
membrane,  306 

Of  pulp,  187 
Fibroma,  endosteal,  333,  385 

Of  jaws,  330,  331,  357,  359 

Of  periodontal  membrane,  265 

Periosteal,  333 
Follicular  odontome,  376,  385 

Bland-Sutton  on,  377,  381 

Heath  on,  382 

Paul  on,  382 

Tomes  and  Nowell  on,  381 
Fracture  of  teeth,  183 

Storer-Bennett  on,  185 
Fungi  imperfecta,  412,  413 
Fungoid  excavation  of  enamel,  34 

Gangrene  of  pulp,  168 

Schenk  on,  171,  172,  173 
Gassmann  on  chemical  differences  in 

dental  tissues,  218 
Gemination  of  teeth,  43 

Diphyodontic,  50 

False,  43,  44,  46,  47 

True,  43,  46,  49 


474 


INDEX 


Gingivitis,  322 

Goadby  on  Bacillus  necrodentalis,  209, 

455 
Gonococcus,  420,  424 
Granulation  tissue,  294 
Gum,  diseases  of,  322 

Endothelioma  of,  340 

Epithelioma  of,  343 

Fibroma  of,  331 

Hypertrophy  of,  3  24 

Inflammation  of,  322 

Papilloma  of,  340 

Sarcoma  of,  334 

Syphilis  of,  348 
Gumaisthenic  perceptions,  224 
Gumma  of  palate,  348,  349 

Halisteresis,  57,  282,  283 
Haemangioma  of  palate,  342 
Haemolytic  streptococci,  425 
Head  on  disturbances  of  sensation,  235 
Healing  processes  in  dental  pulp,  1 74 
Hektoen     and     Riesman     on     "  Cell 
Nests,"  347 

On  Inflammation,  152 

On  Osteitis  rarefaciens,  285 
"Hutchinsonian  teeth,"  20 
Hyaline  adventitious  dentine,  74 
Hydropic  degeneration  of  epithelium, 

330,  360 
Hyperemia  of  pulp,  144 

Bodecker  on,  148 

Etiology  of,  145 

Regional,  212 
Hyperostosis"^ of  jaws,  351,  352 
Hyperplasia  of  cementum,  86 

Of  dental  pulp,  165 
Hypertrophy  of  gum,  324 

Roe  on,  327 
Hyphomycetes  (Moulds),  410,  412 
Hypoplasia  of  enamel,  4 

Impacted  fractures  of  teeth,  183 
Inflammation,  histology  of,  151 
Inflammation  of  antrum,  349 

Of  periodontal  membrane,  254 

Of  pulp,  151 
Injuries  of  pulp,  174 
Internal  absorption  of  dentine,  64 


Internal  absorption  of  enamel,  26 

Woods  on,  26 
"Interruption  lines"  in  enamel  hypo- 
plasia, 7 
lodococcus  vaginatiis,  444 

Jaws,  carcinoma  of,  344 

Exostosis  of,  349 

Fibroma  of,  330,  331,  357,  359 

Hyperostosis  of,  351,  352 

Sarcoma  of,  352 
Jeserich    on    "translucent    zone"    of 
caries,  119 

Keratin,  357,  358 

Karyoclasis,  366 

Karyolysis,  360 

Kirk  on  "bacterial  plaques,"  108 

Kolliker  on  lacunae  in  cementum,  8g 

Lacuna,  arborescent,  92 

Cemental,  89 

Encapsuled,  92 

Kolliker  on,  89 

Plumiliform,  90 

Rimous,  92 
Lacunar  absorption,  57 
Laminar  adventitious  dentine,  76 
Leber  and  Rottenstein  on  "translucent 

zone"  of  caries,  118 
Leon  Williams  on  caries  of  enamel,  107, 
no 

On  syphilitic  enamel,  21 
Lepkowski     on    vascular     supply     of 

dental  tissues,  233 
Leptothrix,  415 
Leptothrix  buccalis  maxima,   132 

Innominata,  448 

Racemosa,  449 
Lesions  of  dental  pulp,  carious,  207 

Chemical  origin  of,  221 

Electrical  origin  of,  221 

Non-carious,  219 

Tactile  origin  of,  219 

Thermal  origin  of,  220 
Leuwenhoek's  materies  alba,  449 
Lingua  nigra,  441 
Lipogenesis,  277 
"Liquefaction  foci,"  130,  135 


INDEX 


475 


Loos  on  senile  changes  in  dentine  and 

pulp,  213 
Ludwig's  angina,  427 

Malignant  degeneration  of  oral  epi- 
thelium, 356 
Malignant  pustule,  433 
Mast   cells,   326 

Melanotic  sarcoma  of  palate,  339 
Materies  alba,  449 
Meningococcus,  420,  424 
Micrococcus,  413 
Micrococcus  alhus,  419,  421 

Aureus,  419,  421,  422,  423 

Catarrhalis,  420,  423 

Citreus,  419,  421 

Tetragenus,  420,  444 
Micro-organisms  of  dental  caries,  139, 

435 
Microspira,  414 

Miller  on  opaque  zones  of  caries,  128 
On    "pipe-stem"    appearance   of 

caries,  135 
On  "translucent  zone"  of  caries, 
117,  119 
Moulds,  410,  412 
Mucous  membrane,   degeneration  of, 

356 
MycobacteriacecB,  414 
Mycobacterium,  414,  432 
Myxothallo phyla,  412 

Nanoid  dentine,  54 

enamel,  16 
Nasmyth's     membrane,     pathological 

affections  of,  102 
Nodules  of  cementum,  80 

Of  enamel,  9 

Of  pulp,  198,  202 
Non-carious  lesions  of  hard  tissues,  219 

Obscure  reflex  acts,  223 
Odontalgig.  223,  226,  231,  235 
Odontoceles,  extracapsular,   399,  400, 
404 

Subcapsular,  399,  400 
Odontomes,  371 

Bland-Sutton  on,  371,  381 

Capsule  of,  394 


Odontomes,   composite,  371,  372,  391 

Epithelial,  330,  352,  371,  372,  400, 
401 

Follicular,  330,  352,  371,  376,  377, 
385,  386 

Radicular,  371,  386 
Oidium  albicans,  354,  421,  439 
Oomycetes,  413 
Opaque  zone  in  caries,  128 
Ophthalmia  neonatorum,  425 
Oral  microbiology,  409 
Osteitis  rarefaciens,  285,  303 
Osteoma  of  jaws,  330,  331,  343 
Osteoporous  atrophy  of  bone,  283 

Nikiforoff  on,  277 
Ousaisthenic  perceptions,  225 
Ovarian    teeth,    attachments   of,    468 

Development  of,  462 

Dentine  of,  467 

Erosion  of,  467 

Eruption  of,  463 

Nasmyth's  membrane  of,  465 

Of  testis,  468 

Shedding  of,  464 

Varieties  of,  462 

Pain  referred,  223 
Palate,  carcinoma  of,  330 

Cavernous  angioma  of,  342 

Hasmangioma  of,  342 

Melanotic  sarcoma  of,  339 

Papilloma  of,  340 
Papilloma  of  gum,  330,  340 

Of  palate,  340 
Pathogenic  micro-organisms,  419 
Pathology  of  pulp,  206 
Periodontal    membrane   (see  Alveolo- 

dental  periosteum). 
Periosteal  fibroma,  333 
Phagocytosis,  153 
Phragmidiothrix,  415 
Phy corny cetes,  413 
Pickerill  on  dental  caries,  106 

On  dentine,  53,  76 
Pigmentation  of  enamel,  7,  14 
"Pipe-stem"  appearance  in  caries,  134 
Planococcus,  413 
Planosarcina,  414 
Pneumococcus,  420,  425,  430,  431 


476 


INDEX 


Pont    on    "sclerosed    conditions"    of 

pulp,  1 68 
Proteus  vulgaris,  140 
Protozoa,  415 
Psendomonas,  414 
Pteridophyta,  413 
Pyogenic  cocci,  421 
"Pyorrhoea  alveolaris,"  271,  422,  431, 
442 
Znamensky  on,  272,  303 

Rachitic  enamel,  18 
Ray  fungus,  435 
Referred  pain,  223 
Reflex  acts,  obscure,  223 
Rhizopus  nigrans,  421 
Rhodobacteriacea,  415 
Russell's  fuchsine  bodies,  261 

Saccharomyces,  37,  40,  439 

Albicans,  439 

Nigrans,  441 
Sarcina,  140,  413,  414 
Sarcodina,  421 

Sarcoma    of    periodontal    membrane, 
264,  265 

Diagnosis  of,  328 

Melanotic,  339 

Myeloid,  337 

Round-celled,  336 

Spindle-celled,  334 
Schenk  on  gangrene  of  pulp,  171 
Schizomycetes,  411,  413 
Schizophycece,  413 
Schizophyta,  411 
"Secondary  enamel  decay,"  114,  115, 

141 
Senile  cementum,  100 

Dentine,  76 

Pulp,  213 
"Setting  the  teeth  on  edge,"  224 
Somaisthenic  ideas,  225 
Spermatogams,  412 
"Spiny"  cells  of  fibromata,  334 
Spirillacea,  414 

Spirillum  sputugenum,  141,  452 
S pirochata,  414 
SpirochcEta  dentium,  141 

Pallida,  20,  420 


Spirosoma,  414 

Stains  on  Nasmyth's  membrane,  102 
Staphylococcus    pyogenes    albus,     139, 
140,  421 

Aureus,  421 

Citreus,  421 
Stomatitis,  348,  354 

Aphthous  ("Thrush"),  354 

Catarrhal,  354 

Gangrenous,  354 

Herpetic,  354 

Mercurial,  354 

Syphilitic,  354 

Ulcerative,  354 
Streptococci,  425 

Streptococcus  pyogenes,  139,  140,  413, 
420,  425,  427 

Viridans,  425 
Streptothrix  actinomyces,  435 

Buccalis,  141 
Subcapsular  odontocele,  400 
Synostosis  {see  Ankylosis). 
Syphilis  of  gum,  348 
Syphilitic  dentine,  21 

Enamel,  19 

Stomatitis,  348,  354 
Systematic  dental  histories,  216 

Tanzer  on  blood  pressure  in  pulp,  226, 

23s 
Thallophyta,  413 
Thiobacteriacece,  415 
"Thrush,"  354 

Tomes  on  calcification  of  pulp,  180 
On  Fungoid  excavation  of  teeth, 

34 
Tomes  and  Nowell  on  dental  caries, 

106 
Torus  palatinus,  330 
"Translucent  zone"  of  caries,  116, 117, 

118,  119,  121,  142,  211 
Treponema,  414,  415,  438 
Trichomonas,  415,  421 
Truman  on  coagulants,  208 
Tuberculosis,  355 
Tumours,  adenoma,  328,  343 
Carcinoma,  328,  343 
Connective  tissue,  328 
Enchondroma,  328,  352 


INDEX 


477 


Tumours,  endothelioma,  328 
Epithelial,  328 
Fibroma,  328,  330,  331 
Glandular,  328 
Haemangioma,  342 
Heterologous,  327 
Homologous,  327 
Innocent,  327 
Lipoma,  328 
Malignant,  327 
Of  mandible,  330 
Of  maxillae,  329 
Of  palate,  330 
Osteoma,  330,  331,  343 
Papilloma,  330,  340 
Sarcoma,  328,  334,  337,  339,  352 
Teratoma,  328,  459 

Underwood  on  erosion,  32 
Unna's  cells,  326 

Vascular  canals  in  dentine,  55 
Lesions  of  dental  pulp,  232 
Vicentini  on  Leptothrix  racemosa,  451 

Walkhoff  on  atrophy  of  pulp,  195 
On  affections  of  Nasmyth's  mem- 
brane, 105 


Walkhoff     on     translucent     zone     of 

caries,  120 
Wedl  on  translucent  zone  of  caries,  122 
Wellauer  on  translucent  zone  of  caries, 

120 
Woods  on  absorption  of  enamel,  26 

Yeasts,  410,  412,  440,  441 

Znamensky  on  erosion  of  enamel,  31 
On  "Fyorrhcea     alveolaris,"     272, 

303 
Zone  of  translucency,  116,  117 

Baume  on,  120 

Bennett  on,  118 

Black  on, 118 

Complete  decalcification,  114 

Leber  and  Rottenstein  on,  1 1 8, 1 2 1 

Magitot  on,  117 

Miller  on,  117,  119 

Tomes  on,  117 

Walkhoff  on,  105,  120 

Wedl  on,  118,  122 

Wellauer  on,  120 
Zones  in  caries  of  enamel,  114 
Zsigmondy  on  hypoplasia  of  enamel   5 
Zyg07nycetes,  413,  421 


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5 


e- 


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Hopewell- Smith 


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Normal  and  pathological  ^^tgr^y 


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The  normal  and  pathplo^ical,histo|og^^| ot 


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